Learn < Doing

Using Jquery Template Plugin

noreply@blogger.com (Anonymous) — Sun, 27 Nov 2011 14:34:00 +0000

&lt;p&gt;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;its Amazing tool ...lets look how easy to template the code using this ......must try this if you are a web developer &amp;lt;/p&amp;gt;&amp;lt;/div&amp;gt;&lt;/p&gt;

Amazing Fails

noreply@blogger.com (Anonymous) — Sat, 26 Nov 2011 18:44:00 +0000

ChromeBooks

noreply@blogger.com (Anonymous) — Wed, 23 Nov 2011 09:17:00 +0000

101 Reasons why I LOVE YOU !!!!!!!!!!

noreply@blogger.com (Anonymous) — Sun, 20 Nov 2011 18:17:00 +0000

1. I love the way we finish each other's sentences.

2. I love the way I know you'll never give up on me.

3. I love the fact that I wouldn't ever give up on you.

4. I love the way you look at me.

5. I love how beautiful your eyes are.

6. I love the way I can't imagine a day without you in my life.

7. I love the way if we were ever separated I wouldn't know how to go on.

8. I love the way we cuddle and watch sunsets together.

9. I love the way we sometimes stay up all night, then watch the sunrise together.

10. I love how I know you'll always be there when I need you to be.

11. I love the fact that I will always be there for you too.

12. I love how when I dream of my life partner, the only person I can see is you.

13. I love how complete I feel when I am with you.

14. I love how our bodies just fit together.

15. I love the way you make me laugh.

16. I love the way you laugh.

17. I love the way you won't compromise yourself when we are together.

18. I love the way you won't let me compromise myself.

19. I love your thoughtfulness.

20. I love your tenderness.

21. I love your ability to speak without saying a single word.

22. I love the way we glance at each other across the room and know what each other is thinking.

23. I love the way, how even though we may be miles apart I still feel like you're right here with me.

24. I love the way you surprise me with the perfect gifts that show you pay attention to me.

25. I love the way you'll watch a sporting game with me even though you may not be interested in it.

26. I love the way you treat my friends.

27. I love your love for the things that interest me.

28. I love the way you let me live my life freely without jealousy.

29. I love how you demand respect but are not controlling.

30. I love how I would do anything in this world to make you happy.

31. I love how you would do anything in this world to make me happy.

32. I love the way your voice sounds over the phone.

33. I love the way your voice sounds when you whisper sweet nothings in my ear.

34. I love the completeness and oneness I feel when we make love.

35. I love your sensuality.

36. I love how our romance feels like the perfect romance movie.

37. I love how you are my soul mate.

38. I love the way you handle troubled times.

39. I love the way you respect me.

40. I love the way you protect and defend me.

41. I love how you feel when we cuddle.

42. I love the softness of your lips against mine.

43. I love the softness of you lips against my body.

44. I love the feeling of your hair brushing against me when we make love.

45. I love laying in bed at night talking about nothing.

46. I love waking up to find we've been cuddling together all night.

47. I love the surprises you leave for me.

48. I love your intelligence.

49. I love your ingenuity.

50. I love your ability to make friends where ever we go.

51. I love your love for life.

52. I love your passion for your hobbies and interests.

53. I love how every time I look at you, you take my breath away.

54. I love how I thank God everyday for bringing someone as wonderful as you into my life.

55. I love the fact you gave me the gift of our children.

56. I love the special moments that we shared that will remain my fondest memories of you and I.

57. I love spending the holidays with the one person I love the most.

58. I love how my heart skips a beat whenever you walk into the room.

59. I love how you love me.

60. I love how I love you.

61. I love the ways you choose to show your affection for me.

62. I love the way you inspire me to be more than I am.

63. I love the way you spark my creativity and imagination.

64. I love the way you make me feel like anything is possible as long as I'm with you.

65. I love your sense of humor.

66. I love the way you make me feel like royalty.

67. I love the way you dress.

68. I love your understated elegance.

69. I love you just the way you are.

70. I love your spontaneity.

71. I love our life together.

72. I love how if I died right now I would be the happiest person alive knowing I found my one true love.

73. I love the fact that we will grow old together.

74. I love your way with words.

75. I love the way you look when your sleeping.

76. I love the way you think you look awful when you first wake up when it is actually then I find you the most beautiful.

77. I love your willingness to share everything and most especially your heart with me.

78. I love your strength of character.

79. I love taking showers together.

80. I love the way you leave me love notes to find whenever you're gone.

81. I love the way you treat me.

82. I love the way you take care of us.

83. I love your cooking.

84. I love the way you take the time to thank me for doing every day things.

85. I love the way you show your affection when we are around friends andor family.

86. I love the way you are not scared to show your affection when we are in public.

87. I love your confidence.

88. I love your ability to make me feel better when times are tough.

89. I love the way we make up after a fight.

90. I love how you treat our children.

91. I love the way you support me when I'm off track.

92. I love the way you take the time to show me how much you love me.

93. I love your beautiful hair.

94. I love your body.

95. I love your openness to try new things.

96. I love your ability to talk things through.

97. I love your courage to be you.

98. I love your greatness.

99. I love the fact that you want to be with me and only me.

100. I love how I am and feel when I am with you!

101. I love you for you! :'my fav 1'

Jai Baba Ramdev ka ASAR

noreply@blogger.com (Anonymous) — Fri, 07 Oct 2011 09:05:00 +0000

******************************

--

Have A Nice Time

Top 100 open source Web Development Tools and applications

noreply@blogger.com (Anonymous) — Mon, 26 Sep 2011 11:40:00 +0000

Web development tools which are open source have great benefits, including free to use and modify code. Thus lately I have been rigorously mapping all the free and open source apps & tools that are useful and easy to use for web developers. Many I have used or come across during my routines. So presented below you can find the 100 Best tools and applications oriented towards the efficient web developer..
Note I will possibly have missed some notable web development tools in this list of open source apps but feel free to comment on any tools or applications you would like added to this list..

Code Editors

1. Aptana

The Aptana IDE is a free, open-source, cross-platform, JavaScript-focused development environment for building Ajax applications. It features code assist on JavaScript, HTML, and CSS languages, FTP/SFTP support and a JavaScript debugger to troubleshoot your code.
Read more on Aptana

2. Eclipse

Eclipse is an open-source software framework written primarily in Java. In its default form it is a Java IDE, consisting of the Java Development Tools (JDT) and compiler (ECJ). Users can extend its capabilities by installing plug-ins written for the Eclipse software framework, such as development toolkits for other programming languages, and can write and contribute their own plug-in modules. Language packs are available for over a dozen languages. (Source Wikipedia)
Read more on Eclipse

3. jEdit

jEdit is a mature programmer’s text editor with hundreds (counting the time developing plugins) of person-years of development behind it. Being a Java based solution it runs across multiple operating systems including; Mac OS X, OS/2, Unix, VMS and Windows.
Read more on jEdit

4. NVU

A Web Authoring System for Linux desktop users as well as Microsoft Windows and Macintosh users to rival programs like FrontPage and Dreamweaver. Nvu (which stands for "new view") makes managing a web site a snap. Now anyone can create web pages and manage a website with no technical expertise or knowledge of HTML.
Read more on NVU

5. Quanta Plus

Quanta Plus is a highly stable and feature rich web development environment. The vision with Quanta has always been to start with the best architectural foundations, design for efficient and natural use and enable maximal user extensibility.

6. Amaya

Amaya is a Web editor to create and update documents directly on the Web. Browsing features are seamlessly integrated with the editing and remote access features in a uniform environment. This follows the original vision of the Web as a space for collaboration and not just a one-way publishing medium. Amaya started as an HTML + CSS style sheets editor. Since that time it was extended to support XML and an increasing number of XML applications such as the XHTML family, MathML, and SVG. It allows all those vocabularies to be edited simultaneously in compound documents.
Read more on Amaya

Modelling Tools

7. Dia

Dia is inspired by the commercial Windows program ‘Visio’, though more geared towards informal diagrams for casual use. It can be used to draw many different kinds of diagrams. It currently has special objects to help draw entity relationship diagrams, UML diagrams, flowcharts, network diagrams, and many other diagrams. It is also possible to add support for new shapes by writing simple XML files, using a subset of SVG to draw the shape.
Read more on Dia

8. ArgoUML

ArgoUML is the leading open source UML modeling tool and includes support for all standard UML 1.4 diagrams. It runs on any Java platform and is available in ten languages.
Read more on ArgoUML

9. StarUML

StarUML is an open source project to develop fast, flexible, extensible, feature rich, and freely-available UML/MDA platform running on Win32 platform. The goal of the StarUML project is to build a software modeling tool and also platform that is a compelling replacement of commercial UML tools such as Rational Rose.
Read more on StarUML

10. MagicDraw

MagicDraw is a visual UML modeling and CASE tool with teamwork support. Designed for Business Analysts, Software Analysts, Programmers, QA Engineers, and Documentation Writers, this dynamic and versatile development tool facilitates analysis and design of Object Oriented (OO) systems and databases. It provides the industry’s best code engineering mechanism (with full round-trip support for J2EE, C#, C++, CORBA IDL programming languages, .NET, XML Schema, WSDL), as well as database schema modeling, DDL generation and reverse engineering facilities.
Read more on MagicDraw

11. OpenOffice Draw

DRAW - from a quick sketch to a complex plan, DRAW gives you the tools to communicate with graphics and diagrams.
Read more on OpenOffice Draw

12. Kivio

Kivio is an easy to use diagramming and flowcharting application with tight integration to the other KOffice applications. It enables you to create network diagrams, organisation charts, flowcharts and more.
Read more on Kivio

File Transfer Clients

13. FileZilla

FileZilla is a free FTP client and a server solution. FileZilla is open source software distributed under the terms of the GNU General Public License.
Read more on Filezilla

14. WinSCP

WinSCP is an open source SFTP client and FTP client for Windows. Its main function is the secure file transfer between a local and a remote computer. Beyond this, WinSCP offers basic file manager functionality. It uses Secure Shell (SSH) and supports, in addition to Secure FTP, also legacy SCP protocol.
Read more on WinSCP

15. CyberDuck

Cyberduck is an open source FTP and SFTP (SSH Secure File Transfer) browser licenced under the GPL with an easy to use interface, integration with external editors and support for many Mac OS X system technologies such as Spotlight, Bonjour, the Keychain and AppleScript.
Read more on CyberDuck

16. FireFTP

FireFTP is a free, secure, cross-platform FTP client for Mozilla Firefox which provides easy and intuitive access to FTP servers.
Read more on FireFTP

Code Documentors

17. JSDoc

JSDoc is a tool that parses inline documentation in JavaScript source files, and produces an documentation of the JavaScript code. This is typically in the form of HTML, but XML and XMI (UML) export are also supported. JSDoc is based on the (very successful) javadoc tool that was created for the same purpose for the Java programming language.

18. Javadoc

Javadoc is a tool for generating API documentation in HTML format from doc comments in source code. It can be downloaded only as part of the Java 2 SDK.
Read more on Javadoc

19. PHPDoc

PHPDoc is an adoption of Javadoc to the PHP world. PHPDoc is written in PHP. It offers you a way to generate an API documentation of objectoriented and procedural code with certain markup in your source. PHPDoc is an Open Source Project and gets distributed under the PHP Licence. That means you can use it in commercials projects.
Read more on PHPDoc

20. phpDocumentor

phpDocumentor, sometimes referred to as phpdoc or phpdocu, is the current standard auto-documentation tool for the php language. Similar to Javadoc, and written in php, phpDocumentor can be used from the command line or a web interface to create professional documentation from php source code. phpDocumentor has support for linking between documentation, incorporating user level documents like tutorials and creation of highlighted source code with cross referencing to php general documentation. A complete list of features is available.

Read more on phpDocumentor

Browser Plugins

21. ColorZilla

Advanced Eyedropper, ColorPicker, Page Zoomer and other colorful goodies.
Read more on ColorZilla

22. LiveHTTPHeaders

LiveHTTPHeaders displays http headers in real time (while pages are being downloaded from the Internet) letting you edit request headers and replay a URL.
Read more on LiveHTTPHeaders

23. DebugBar

The DebugBar V4.1.1 is an Internet Explorer plug-in that brings you new powerful features such as a DOM Inspector, HTTP Inspector, JavaScript Inspector, JavaScript Console and HTML Validator.
Read more on DebugBar

24. Firebug

Firebug integrates with Firefox to put a wealth of web development tools at your fingertips while you browse. You can edit, debug, and monitor CSS, HTML, and JavaScript live in any web page.
Read more on Firebug

25. Firebug Lite

Well this one isn’t a browser plugin as such, however I think it goes nicely under Firebug.
Firebug Lite is a JavaScript file you can insert into your pages to simulate the Firebug console in browsers that are not named "Firefox".
Read more on Firebug Lite

26. FireBug Lite ++ (IE7Pro)

An amelioration of the FireBug Lite Script used as userscript for observing from all web sites. F12 to open the console
FireBug Lite ++ can :
- Observe errors
- Evaluate expression (console)
- Browse JavaScript Object (not in FireBug lite, added by this script !)
Read more on FireBug Lite ++ (IE7Pro)

27. Internet Explorer Toolbar

The Microsoft Internet Explorer Developer Toolbar provides a variety of tools for quickly creating, understanding, and troubleshooting Web pages. This version is a preview release and behavior may change in the final release.

Read more on Internet Explorer Toolbar

28. Firefox web developer toolbar

The Web Developer extension adds a menu and a toolbar to the browser with various web developer tools. It is designed for Firefox, Flock, Mozilla and Seamonkey, and will run on any platform that these browsers support including Windows, Mac OS X and Linux.

Read more on Firefox we developer toolbar

29. IE7Pro

IE7Pro is a must have add-on for Internet Explorer, which includes a lot of features and tweaks to make your IE friendlier, more useful, secure and customizable. IE7Pro includes Tabbed Browsing Management, Spell Check, Inline Search, Super Drag Drop, Crash Recovery, Proxy Switcher, Mouse Gesture, Tab History Browser, Web Accelerator, User Agent Switcher, Webpage Capturer, AD Blocker, Flash Block, Greasemonkey like User Scripts platform, User Plug-ins and many more power packed features. You can customize not just Internet Explorer, but even your favorite website according to your need and taste using IE7Pro.
Read more on IE7Pro

30. Opera Web Developer Toolbar & Menu

The web developer toolbar is a menu and toolbar setup for Opera which brings together functions related to web development, validation services and links to standards and other documentation. It integrates parts of Toby’s W3-dev Menu, MooseCSS’s menu, and countless BookMarklets taken from various places (Jesse, Aleto, SlayerOffice, Tarquin and others).
Read more on Opera Web Developer Toolbar & Menu

31. Pearl Cresent

Pearl Crescent Page Saver is an extension for Mozilla Firefox that lets you capture images of web pages. These images can be saved in PNG or JPEG format. Using Page Saver, you can capture an entire page or just the visible portion. Options let you control whether images are captured at full size (which is the default) or scaled down to a smaller size.
Read more on Perl Cresent

32. Feng GUI FireFox Add-On extension

A plugin allowing you to easily find out how people View your website or image and which areas are getting most of the attention.
The ViewFinder Heatmap service, is an artificial intelligence service which simulates human visual attention and creates an attention heatmap.
Read more on Feng GUI FireFox Add-On extension

33. Lorem Ipsum Content Generator 0.4

The Lorem Ipsum Content Generator creates placeholder content using latin pasages. This allows you to see what a page is going to look like with content before the copy is actually available.

34. FlashBlock

Flashblock is an extension for the Mozilla, Firefox, and Netscape browsers that takes a pessimistic approach to dealing with Macromedia Flash content on a webpage and blocks ALL Flash content from loading. It then leaves placeholders on the webpage that allow you to click to download and then view the Flash content.
Read more on FlashBlock

Unit Testing

35. PHPUnit

I understand this is a framework, however, I think it’s a good tool to use in PHP development.
To make code testing viable, good tool support is needed. This is where PHPUnit comes into play. It is a member of the xUnit family of testing frameworks and provides both a framework that makes the writing of tests easy as well as the functionality to easily run the tests and analyse their results.
Read more on PHPUnit

36. JUnit

JUnit is a simple framework to write repeatable tests. It is an instance of the xUnit architecture for unit testing frameworks.
Read more on JUnit

37. JsUnit

JsUnit is a Unit Testing framework for client-side (in-browser) JavaScript. It is essentially a port of JUnit to JavaScript. Also included is a platform for automating the execution of tests on multiple browsers and mutiple machines running different OSs.
Read more on JsUnit here
38. NUnit
NUnit is a unit-testing framework for all .Net languages. Initially ported from JUnit, the current production release, version 2.4, is the fifth major release of this xUnit based unit testing tool for Microsoft .NET. It is written entirely in C# and has been completely redesigned to take advantage of many .NET language features, for example custom attributes and other reflection related capabilities. NUnit brings xUnit to all .NET languages.
Read more on NUnit

Load/Stress Testing

39. OpenSTA

OpenSTA is a distributed software testing architecture designed around CORBA, it was originally developed to be commercial software by CYRANO. The current toolset has the capability of performing scripted HTTP and HTTPS heavy load tests with performance measurements from Win32 platforms.
Read more on OpenSTA

40. curl-loader

A powerful C-written HTTP, HTTPS, FTP, FTPS load generator, performance and stress testing tool. It uses real HTTP and TLS/SSL stacks, generating thousands of users each with own IP-address. Emphases is given to user authentication, login and statistics.
Read more on curl-loader

Usability/Accessibility and General Testing

41. Xenu

Xenu’s Link Sleuth (TM) checks Web sites for broken links. Link verification is done on "normal" links, images, frames, plug-ins, backgrounds, local image maps, style sheets, scripts and java applets. It displays a continously updated list of URLs which you can sort by different criteria. A report can be produced at any time.

Read more on Xenu

42. Vischeck

Vischeck is a way of showing you what things look like to someone who is color blind. You can try Vischeck online- either run Vischeck on your own image files or run Vischeck on a web page. You can also download programs to let you run it on your own computer.
Read more on Vischeck

43. browsershots.org

Browsershots.org is a free open-source online service providing screenshots of your web site in a multitude of different browsers. It is not as advanced as BrowserCam but a fantastic tool none the less.
Read more on browsershots.org

44. BrowsrCamp

If you need to test your websites on MacOSX browsers then this service is the perfect place for you. BrowsrCamp offers two services: a Safari screenshots generator (free) and a testing system based on VNC (paid).
Read more on BrowsrCamp

45. Feng GUI

Find out how people View your website or image and which areas are getting most of the attention.
The ViewFinder Heatmap service, is an artificial intelligence service which simulates human visual attention and creates an attention heatmap.
Read more on Feng GUI

46. Watchfire WebXACT

WebXACT is a free online service that lets you test single pages of web content for quality, accessibility, and privacy issues. It is very similar to Bobby and usefull to anyone wishing to check the accessibilty level of their templates/site.

47. DBMonster

DBMonster is a tool which generates random test data and puts it into SQL database. It helps to test how an application can deal with large database.
Read more on DBMonster

Regular Expressions

48. Expresso 2.1

Expresso is useful tool for learning how to use regular expressions and for developing and debugging regular expressions prior to incorporating them into your code. It provides a very cut down version of RegexBuddy but most importantly it is simple to use and free.
Read more on Expresso 2.1

49. Regex Coach

The Regex Coach is a graphical application for Windows which can be used to experiment with (Perl-compatible) regular expressions interactively.
Read more on Regex Coach

Image Editing

50. GIMP

The GNU Image Manipulation Program is a Photoshop replacement that doesn’t have "quite" as much functionality but it’s excellent for free. It comes installed by default on many Linux distros and is also available in Windows. Worth a look.
Read more on GIMP

51. Inkscape

Inkscape is an Open Source vector graphics editor, with capabilities similar to Illustrator, Freehand, CorelDraw, or Xara X using the W3C standard Scalable Vector Graphics (SVG) file format.
Read more on Inkscape

52. Paint.net

A really good, lightweight alternative to Photoshop. It offers layers, unlimited undo, special effects and a wide variety of useful tools. The download is around 2mb too so absolutely worth a look – I use this when Photoshop is playing up.
Read more on Paint.net

53. XnView

XnView is software to view and convert graphic files, apparently really simple to use and supports more than 400 graphics formats.
Read more on XnView

54. ImageMagick

A lesser known application but it offers the ability to "create, edit, and compose bitmap images. It can read, convert and write images in a variety of formats (about 100)". Use it to "translate, flip, mirror, rotate, scale, shear and transform images, adjust image colors, apply various special effects, or draw text, lines, polygons, ellipses and B?zier curves."
Read more on ImageMagick

55. Blender

A 3D Studio Max alternative, very comprehensive and full-featured.
Read more on Blender

56. Pencil

Pencil is an animation/drawing software for Mac OS X and Windows. It lets you create traditional hand-drawn animation (cartoon) using both bitmap and vector graphics. Pencil is free and open source.
Read more on Pencil

57. Artweaver

Artweaver is a simple Freeware program for creative painting, i.e. Artweaver offers you all artistic effects which you need for your work. You can create sketches from photos and experiment with a wide range of brushes. The brush simulation is thereby so realistic as possible.
Read more on Artweaver

Colour Matching and Sampling

58. ColorJack

ColorJack is an amazing online application providing users with the ability to match colours that work well together. Perfect for those developers who struggle to get a good colour scheme together.
Read more on ColorJack

59. Kuler

Kuler is a very nice application allowing you match colours that will “work well” together. Also allows you to see other people colour pallets. A good starting place and very cool.
Read more on Kuler

60. Color Cop

A very handy tool for capturing colours anywhere on your screen. Color Cop makes it quick and easy in those situations where you need to know what colour is being used.
Read more on Color Cop

Database Design

61. DBDesigner 4

DBDesigner 4 is a visual database design system that integrates database design, modeling, creation and maintenance into a single, seamless environment.
It combines professional features and a clear and simple user interface to offer the most efficient way to handle your databases.
Read more on DBDesigner 4

62. Clay

Clay is a database design tool that runs as a plug-in in the Eclipse development environment. Clay has an intuitive user interface for graphically designing database models. Clay can also create a database model by reverse engineering an existing database. Furthermore, Clay generates the SQL (DDL) code appropriate for your database.
Read more on Clay

Source Control

63. Subversion

The goal of the Subversion project is to build a version control system that is a compelling replacement for CVS in the open source community. The software is released under an Apache/BSD-style open source license.
Read more on Subversion

64. CVS

CVS is a version control system, an important component of Source Configuration Management (SCM). Using it, you can record the history of sources files, and documents. It fills a similar role to the free software RCS, PRCS, and Aegis packages.
Read more on CVS

65. CVSNT

The CVSNT Versioning System implements a version control system: it keeps track of all changes in a set of files, typically the implementation of a software project, and allows several (potentially geographically separated) developers to collaborate. It is compatible with and originally based on Concurrent Versions System (CVS), which has become popular in the open-source world and is released under the GNU General Public License. (Source Wikipedia)
Read more on CVSNT

66. RapidSVN

RapidSVN is a cross-platform GUI front-end for the Subversion revision system written in C++ using the wxWidgets framework. This project also includes a Subversion client C++ API.
Read more on RapidSVN

67. TortoiseSVN

A Subversion client, implemented as a windows shell extension. TortoiseSVN is a really easy to use Revision control / version control / source control software for Windows.
Since it’s not an integration for a specific IDE you can use it with whatever development tools you like. TortoiseSVN is free to use. You don’t need to get a loan or pay a full years salary to use it.
Read more on TortoiseSVN

68. TortoiseCVS

TortoiseCVS lets you work with files under CVS version control directly from Windows Explorer. It’s freely available under the GPL.
With TortoiseCVS you can directly check out modules, update, commit and see differences by right clicking on files and folders within Explorer. You can see the state of a file with overlays on top of the normal icons within Explorer. It even works from within the file open dialog.
Read more on TortoiseCVS

69. SmartCVS

SmartCVS is an innovative multi-platform CVS client. It has powerful features, like built-in File Compare/Merge, Transaction display or List Repository Files, and still is easy and intuitive to use. SmartCVS focuses on your day-to-day tasks and usability and is not limited to the available CVS command set.
SmartCVS is available in two versions, a free Foundation version and the powerful Professional version.
Read more on SmartCVS

70. Subclipse

Subclipse is an Eclipse Team Provider plug-in providing support for Subversion within the Eclipse IDE. The software is released under the Eclipse Public License (EPL) 1.0 open source license.
Read more on Subclipse

71. JCVS

JCVS is a CVS client package written entirely in Java. JCVS provides a complete CVS client/server protocol package that allows any Java program to implement the complete suite of CVS operations. JCVS also provides a Swing based client that provides a commercial quality GUI client for CVS. Finally, jCVS provides a Servlet that allows any Servlet enabled web server to present any CVS repository on the internet for browsing and download.
Read more on JCVS

72. WinCVS

WinCvs is a CVS client that runs on the Microsoft Windows platform. CVS, Concurrent Versions System, is a centralized Revision Control System (RCS). SourceForge.net provides CVS service to all hosted projects. In order to access our CVS service, you will need to install a CVS client. CVS allows developers to keep a historical record of changes made to their source code tree, and to allow multiple developers to work on a single set of files at the same time without accidentally overwriting changes made by other developers.
Read more on WinCVS

HTTP Debugging

73. Fiddler

Fiddler is a HTTP Debugging Proxy which logs all HTTP traffic between your computer and the Internet. Fiddler allows you to inspect all HTTP Traffic, set breakpoints, and "fiddle" with incoming or outgoing data. Fiddler includes a powerful event-based scripting subsystem, and can be extended using any .NET language.
Read more on Fiddler

74. Fiddler 2

Fiddler is a Web Debugging Proxy which logs all HTTP(S) traffic between your computer and the Internet. Fiddler allows you to inspect all HTTP(S) traffic, set breakpoints, and "fiddle" with incoming or outgoing data. Fiddler includes a powerful event-based scripting subsystem, and can be extended using any .NET language.
Fiddler is freeware and can debug traffic from virtually any application, including Internet Explorer, Mozilla Firefox, Opera, and thousands more.
Read more on Fiddler 2

Servers

75. Apache

The Apache HTTP Server is an open-source HTTP server for modern operating systems including UNIX and Windows NT. It provides a secure, efficient and extensible server that offers HTTP services in sync with the current HTTP standards.
Read more on Apache

76. Apache Tomcat

Apache Tomcat is the servlet container that is used in the official Reference Implementation for the Java Servlet and JavaServer Pages technologies. The Java Servlet and JavaServer Pages specifications are developed by Sun under the Java Community Process.
Read more on Apache Tomcat

77. XAMPP

XAMPP is an easy to install Apache distribution containing MySQL, PHP and Perl. XAMPP is really very easy to install and to use - just download, extract and start.
Read more on XAMPP

Databases

78. MySQL

MySQL is the world’s most popular open source database software, with over 100 million copies of its software downloaded or distributed throughout its history. With superior speed, reliability, and ease of use, MySQL has become the preferred choice of corporate IT Managers because it eliminates the major problems associated with downtime, maintenance, administration and support.
Read more on MySQL

79. PostgreSQL

PostgreSQL, the highly scalable, SQL compliant, open source object-relational database management system, is now undergoing beta testing of the next version of our software: PostgreSQL 8.3.
Read more on PostgreSql

80. Apache Derby

Apache Derby is an open source relational database implemented entirely in Java and available under the Apache License, Version 2.0. Some key advantages include:
• Derby has a small footprint — about 2 megabytes for the base engine and embedded JDBC driver.
• Derby is based on the Java, JDBC, and SQL standards.
• Derby provides an embedded JDBC driver that lets you embed Derby in any Java-based solution.
• Derby also supports the more familiar client/server mode with the Derby Network Client JDBC driver and Derby Network Server.
• Derby is easy to install, deploy, and use.
Read more on Apache Derby

Database Administration

81. pgAdmin

pgAdmin III is the most popular and feature rich Open Source administration and development platform for PostgreSQL, the most advanced Open Source database in the world. The application may be used on Linux, FreeBSD, OpenSUSE, Solaris, Mac OSX and Windows platforms to manage PostgreSQL 7.3 and above running on any platform, as well as commercial versions of PostgreSQL such as EnterpriseDB and Mammoth PostgreSQL.
Read more on pgAdmin

82. MySQL GUI Tools Bundle for 5.0

MySQL GUI Tools Bundle for 5.0 is available under the MySQL AB "dual licensing" model. Under this model, users may choose to use MySQL products under the free software/opensource GNU General Public License (commonly known as the "GPL") or under a commercial license.
This is the MySQL GUI Tools Bundle for 5.0. It includes the following products.
• MySQL Administrator 1.2 Generally Available (GA)
• MySQL Query Browser 1.2 Generally Available (GA)
• MySQL Migration Toolkit 1.1 Generally Available (GA)
Read more on MySQL GUI Tools Bundle for 5.0

83. phpMyAdmin

phpMyAdmin is a tool written in PHP intended to handle the administration of MySQL over the Web. Currently it can create and drop databases, create/drop/alter tables, delete/edit/add fields, execute any SQL statement, manage keys on fields.
Read more on phpMyAdmin

Site Statistics

84. AWStats

AWStats is a free powerful and featureful tool that generates advanced web, streaming, ftp or mail server statistics, graphically. This log analyzer works as a CGI or from command line and shows you all possible information your log contains, in few graphical web pages. It uses a partial information file to be able to process large log files, often and quickly. It can analyze log files from all major server tools like Apache log files (NCSA combined/XLF/ELF log format or common/CLF log format), WebStar, IIS (W3C log format) and a lot of other web, proxy, wap, streaming servers, mail servers and some ftp servers.
Read more on AWStats

85. phpMyVisits

phpMyVisites is a free and powerful open source (GNU/GPL) software for websites statistics and audience measurements.
Read more on phpMyVisits

86. Google Analytics

Google Analytics (GA) is a free service offered by Google that generates detailed statistics about the visitors to a website. Its main highlight is that a webmaster can optimize his/her AdWords advertisement and marketing campaigns through the use of GA’s analysis of where the visitors came from, how long they stayed on the website and their geographical position. (Source Wikipedia)
Read more on Google Analytics

Other

87. Beautify PHP

This program tries to reformat and beautify PHP source code files automatically. It is a pretty printer for your php source code. The program is Open Source and distributed under the terms of GNU GPL. It is written in PHP and has a web frontend.
Read more on Beautify PHP

88. PuTTY

PuTTY is a free implementation of Telnet and SSH for Win32 and Unix platforms, along with an xterm terminal emulator. It is written and maintained primarily by Simon Tatham.
Read more on PuTTY

89. WinMerge

WinMerge is an Open Source visual text file differencing and merging tool for Win32 platforms. It is highly useful for determing what has changed between project versions, and then merging changes between versions.
Read more on WinMerge

90. DBG

DBG is a full-featured php debugger. It works on a production and/or development WEB server and allows you debug your scripts locally or remotely, from an IDE or console.
Read more on DBG

91. PHP Accelerator

The ionCube PHP Accelerator is an easily installed PHP Zend engine extension that provides a PHP cache, and is capable of delivering a substantial acceleration of PHP scripts without requiring any script changes, loss of dynamic content, or other application compromises.
Read more on PHP Accelerator

92. ajaxload.info

Ajax Load is an online application providing the ability to easily create and download “ajax loading“ images for your website or application. Very Web 2.0
Read more on ajaxload.info

93. Stripemania

Ever wanted to create a cool background for your site? Well this site allows you to easily generate your perfect background to use as you wish.
Read more on Stripemania

94. FavIcon Generator

Does exactly what is says on the tin. You upload your desired image and the generator does the rest.

95. YAML Builder

Ever wanted a tool that could build a base HTML Template quickly by allowing you to define the basic layout? Well this is that tool and it works really well too. Definitely worth a look.
Read more on YAML Builder

96. CSS Rounded Box Generator

A simple tool allowing you to quickly and easily generate rounded corners for your website.
Read more on CSS Rounded Corner Generator

97. CSS Optimiser

Online CSS Optimizer/Optimiser is a web tool for reducing the file size of cascading style sheets. In order to save more space optimized files would be messy even so you may output it as a file. Non-valid or hacked (for certain browsers) CSS files may result in error.
Read more on CSS Optimiser

98. CSS Validator

Validates your CSS stylesheets against W3C standards.
Read more on CSS Validator

99. Acrobot

To cut to the chase Acrobot is a tool that takes supplied content and adds in relevant abbreviation or acronym tags.
Read more on Acrobot

100. Markup Validation Service

This validator checks the markup validity of Web documents in HTML, XHTML, SMIL, MathML, etc. If you wish to validate specific content such as RSS/Atom feeds or CSS stylesheets or to find broken links, there are other validators and tools available.
Read more on Markup Validation Service

Original Source:http://www.ajaxlines.com

JAVA Interview Question

noreply@blogger.com (Anonymous) — Thu, 15 Sep 2011 18:05:00 +0000

What is Collection API ?
The Collection API is a set of classes and interfaces that support operation on collections of objects. These classes and interfaces are more flexible, more powerful, and more regular than the vectors, arrays, and hashtables if effectively replaces.
Example of classes: HashSet, HashMap, ArrayList, LinkedList, TreeSet and TreeMap.
Example of interfaces: Collection, Set, List and Map.
Is Iterator a Class or Interface? What is its use?
Answer: Iterator is an interface which is used to step through the elements of a Collection.
What is similarities/difference between an Abstract class and Interface?
Differences are as follows:
Interfaces provide a form of multiple inheritance. A class can extend only one other class. Interfaces are limited to public methods and constants with no implementation. Abstract classes can have a partial implementation, protected parts, static methods, etc.
A Class may implement several interfaces. But in case of abstract class, a class may extend only one abstract class. Interfaces are slow as it requires extra indirection to to find corresponding method in in the actual class. Abstract classes are fast.
Similarities:

Neither Abstract classes or Interface can be instantiated.
Java Interview Questions - How to define an Abstract class?
A class containing abstract method is called Abstract class. An Abstract class can't be instantiated.
Example of Abstract class:
abstract class testAbstractClass {
protected String myString;
public String getMyString() {
return myString;
}
public abstract string anyAbstractFunction();
}

How to define an Interface in Java ?
In Java Interface defines the methods but does not implement them. Interface can include constants. A class that implements the interfaces is bound to implement all the methods defined in Interface.
Emaple of Interface:

public interface sampleInterface {
public void functionOne();

public long CONSTANT_ONE = 1000;
}
If a class is located in a package, what do you need to change in the OS environment to be able to use it?

You need to add a directory or a jar file that contains the package directories to the CLASSPATH environment variable. Let's say a class Employee belongs to a package com.xyz.hr; and is located in the file c:\dev\com\xyz\hr\Employee.java. In this case, you'd need to add c:\dev to the variable CLASSPATH. If this class contains the method main(), you could test it from a command prompt window as follows:
c:\>java com.xyz.hr.Employee
How many methods in the Serializable interface?
There is no method in the Serializable interface. The Serializable interface acts as a marker, telling the object serialization tools that your class is serializable.
How many methods in the Externalizable interface?
There are two methods in the Externalizable interface. You have to implement these two methods in order to make your class externalizable. These two methods are readExternal() and writeExternal().
What is the difference between Serializalble and Externalizable interface?
When you use Serializable interface, your class is serialized automatically by default. But you can override writeObject() and readObject() two methods to control more complex object serailization process. When you use Externalizable interface, you have a complete control over your class's serialization process.
What is a transient variable in Java?
A transient variable is a variable that may not be serialized. If you don't want some field to be serialized, you can mark that field transient or static.
Which containers use a border layout as their default layout?
The Window, Frame and Dialog classes use a border layout as their default layout.
How are Observer and Observable used?
Objects that subclass the Observable class maintain a list of observers. When an Observable object is updated, it invokes the update() method of each of its observers to notify the observers that it has changed state. The Observer interface is implemented by objects that observe Observable objects.

What is Java?
Java is an object-oriented programming language developed initially by James Gosling and colleagues at Sun Microsystems. The language, initially called Oak (named after the oak trees outside Gosling's office), was intended to replace C++, although the feature set better resembles that of Objective C. Java should not be confused with JavaScript, which shares only the name and a similar C-like syntax. Sun Microsystems currently maintains and updates Java regularly.
What does a well-written OO program look like?
A well-written OO program exhibits recurring structures that promote abstraction, flexibility, modularity and elegance.
Can you have virtual functions in Java?
Yes, all functions in Java are virtual by default. This is actually a pseudo trick question because the word "virtual" is not part of the naming convention in Java (as it is in C++, C-sharp and VB.NET), so this would be a foreign concept for someone who has only coded in Java. Virtual functions or virtual methods are functions or methods that will be redefined in derived classes.
Jack developed a program by using a Map container to hold key/value pairs. He wanted to make a change to the map. He decided to make a clone of the map in order to save the original data on side. What do you think of it? ?
If Jack made a clone of the map, any changes to the clone or the original map would be seen on both maps, because the clone of Map is a shallow copy. So Jack made a wrong decision.
What is more advisable to create a thread, by implementing a Runnable interface or by extending Thread class?
Strategically speaking, threads created by implementing Runnable interface are more advisable. If you create a thread by extending a thread class, you cannot extend any other class. If you create a thread by implementing Runnable interface, you save a space for your class to extend another class now or in future.
What is NullPointerException and how to handle it?

When an object is not initialized, the default value is null. When the following things happen, the NullPointerException is thrown:
--Calling the instance method of a null object.
--Accessing or modifying the field of a null object.
--Taking the length of a null as if it were an array.
--Accessing or modifying the slots of null as if it were an array.
--Throwing null as if it were a Throwable value.
The NullPointerException is a runtime exception. The best practice is to catch such exception even if it is not required by language design.
An application needs to load a library before it starts to run, how to code?
One option is to use a static block to load a library before anything is called. For example,
class Test {
static {
System.loadLibrary("path-to-library-file");
}
....
}
When you call new Test(), the static block will be called first before any initialization happens. Note that the static block position may matter.
How could Java classes direct program messages to the system console, but error messages, say to a file?
The class System has a variable out that represents the standard output, and the variable err that represents the standard error device. By default, they both point at the system console. This how the standard output could be re-directed:
Stream st = new Stream(new FileOutputStream("output.txt")); System.setErr(st); System.setOut(st);
What's the difference between an interface and an abstract class?
An abstract class may contain code in method bodies, which is not allowed in an interface. With abstract classes, you have to inherit your class from it and Java does not allow multiple inheritance. On the other hand, you can implement multiple interfaces in your class.
Name the containers which uses Border Layout as their default layout?
Containers which uses Border Layout as their default are: window, Frame and Dialog classes.
What do you understand by Synchronization?
Synchronization is a process of controlling the access of shared resources by the multiple threads in such a manner that only one thread can access one resource at a time. In non synchronized multithreaded application, it is possible for one thread to modify a shared object while another thread is in the process of using or updating the object's value.
Synchronization prevents such type of data corruption.
E.g. Synchronizing a function:
public synchronized void Method1 () {
// Appropriate method-related code.
}
E.g. Synchronizing a block of code inside a function:
public myFunction (){
synchronized (this) {
// Synchronized code here.
}
}

What is synchronization and why is it important?
With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources. Without synchronization, it is possible for one thread to modify a shared object while another thread is in the process of using or updating that object's value. This often causes dirty data and leads to significant errors.
What are synchronized methods and synchronized statements?
Synchronized methods are methods that are used to control access to a method or an object. A thread only executes a synchronized method after it has acquired the lock for the method's object or class. Synchronized statements are similar to synchronized methods. A synchronized statement can only be executed after a thread has acquired the lock for the object or class referenced in the synchronized statement.
What are three ways in which a thread can enter the waiting state?
A thread can enter the waiting state by invoking its sleep() method, by blocking on IO, by unsuccessfully attempting to acquire an object's lock, or by invoking an object's wait() method. It can also enter the waiting state by invoking its (deprecated) suspend() method.
Can a lock be acquired on a class?
Yes, a lock can be acquired on a class. This lock is acquired on the class's Class object.
What's new with the stop(), suspend() and resume() methods in JDK 1.2?
The stop(), suspend() and resume() methods have been deprecated in JDK 1.2.
What is the preferred size of a component?
The preferred size of a component is the minimum component size that will allow the component to display normally.
What's the difference between J2SDK 1.5 and J2SDK 5.0?
There's no difference, Sun Microsystems just re-branded this version.
What would you use to compare two String variables - the operator == or the method equals()?
I'd use the method equals() to compare the values of the Strings and the == to check if two variables point at the same instance of a String object.
What is thread?
A thread is an independent path of execution in a system.
What is multi-threading?
Multi-threading means various threads that run in a system.
How does multi-threading take place on a computer with a single CPU?
The operating system's task scheduler allocates execution time to multiple tasks. By quickly switching between executing tasks, it creates the impression that tasks execute sequentially.
How to create a thread in a program?
You have two ways to do so. First, making your class "extends" Thread class. Second, making your class "implements" Runnable interface. Put jobs in a run() method and call start() method to start the thread.
Can Java object be locked down for exclusive use by a given thread?
Yes. You can lock an object by putting it in a "synchronized" block. The locked object is inaccessible to any thread other than the one that explicitly claimed it.
Can each Java object keep track of all the threads that want to exclusively access to it?
Yes. Use Thread.currentThread() method to track the accessing thread.
Does it matter in what order catch statements for FileNotFoundException and IOExceptipon are written?
Yes, it does. The FileNoFoundException is inherited from the IOException. Exception's subclasses have to be caught first.
What invokes a thread's run() method?
After a thread is started, via its start() method of the Thread class, the JVM invokes the thread's run() method when the thread is initially executed.

What is the purpose of the wait(), notify(), and notifyAll() methods?
The wait(),notify(), and notifyAll() methods are used to provide an efficient way for threads to communicate each other.
What are the high-level thread states?
The high-level thread states are ready, running, waiting, and dead.
What is the difference between yielding and sleeping?
When a task invokes its yield() method, it returns to the ready state. When a task invokes its sleep() method, it returns to the waiting state.
What happens when a thread cannot acquire a lock on an object?
If a thread attempts to execute a synchronized method or synchronized statement and is unable to acquire an object's lock, it enters the waiting state until the lock becomes available.
What is the difference between Process and Thread?
A process can contain multiple threads. In most multithreading operating systems, a process gets its own memory address space; a thread doesn't. Threads typically share the heap belonging to their parent process. For instance, a JVM runs in a single process in the host O/S. Threads in the JVM share the heap belonging to that process; that's why several threads may access the same object. Typically, even though they share a common heap, threads have their own stack space. This is how one thread's invocation of a method is kept separate from another's. This is all a gross oversimplification, but it's accurate enough at a high level. Lots of details differ between operating systems. Process vs. Thread A program vs. similar to a sequential program an run on its own vs. Cannot run on its own Unit of allocation vs. Unit of execution Have its own memory space vs. Share with others Each process has one or more threads vs. Each thread belongs to one process Expensive, need to context switch vs. Cheap, can use process memory and may not need to context switch More secure. One process cannot corrupt another process vs. Less secure. A thread can write the memory used by another thread
Can an inner class declared inside of a method access local variables of this method?
It's possible if these variables are final.
What can go wrong if you replace &emp;&emp; with &emp; in the following code: String a=null; if (a!=null && a.length()>10) {...}
A single ampersand here would lead to a NullPointerException.
What is the Vector class?
The Vector class provides the capability to implement a growable array of objects
What modifiers may be used with an inner class that is a member of an outer class?
A (non-local) inner class may be declared as public, protected, private, static, final, or abstract.
If a method is declared as protected, where may the method be accessed?
A protected method may only be accessed by classes or interfaces of the same package or by subclasses of the class in which it is declared.
What is an Iterator interface?
The Iterator interface is used to step through the elements of a Collection.
How many bits are used to represent Unicode, ASCII, UTF-16, and UTF-8 characters?
Unicode requires 16 bits and ASCII require 7 bits. Although the ASCII character set uses only 7 bits, it is usually represented as 8 bits. UTF-8 represents characters using 8, 16, and 18 bit patterns. UTF-16 uses 16-bit and larger bit patterns.
What's the main difference between a Vector and an ArrayList?
Java Vector class is internally synchronized and ArrayList is not.
What are wrapped classes?
Wrapped classes are classes that allow primitive types to be accessed as objects.
Does garbage collection guarantee that a program will not run out of memory?
No, it doesn't. It is possible for programs to use up memory resources faster than they are garbage collected. It is also possible for programs to create objects that are not subject to garbage collection.
What is the difference between preemptive scheduling and time slicing?
Under preemptive scheduling, the highest priority task executes until it enters the waiting or dead states or a higher priority task comes into existence. Under time slicing, a task executes for a predefined slice of time and then reenters the pool of ready tasks. The scheduler then determines which task should execute next, based on priority and other factors.

Name Component subclasses that support painting ?
The Canvas, Frame, Panel, and Applet classes support painting.
What is a native method?
A native method is a method that is implemented in a language other than Java.
How can you write a loop indefinitely?
for(;;)--for loop; while(true)--always true, etc.
Can an anonymous class be declared as implementing an interface and extending a class?
An anonymous class may implement an interface or extend a superclass, but may not be declared to do both.
What is the purpose of finalization?
The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup processing before the object is garbage collected.
When should the method invokeLater()be used?
This method is used to ensure that Swing components are updated through the event-dispatching thread.
How many methods in Object class?
This question is not asked to test your memory. It tests you how well you know Java. Ten in total.
clone()
equals() & hashcode()
getClass()
finalize()
wait() & notify()
toString()

How does Java handle integer overflows and underflows?
It uses low order bytes of the result that can fit into the size of the type allowed by the operation.

What is the numeric promotion?
Numeric promotion is used with both unary and binary bitwise operators. This means that byte, char, and short values are converted to int values before a bitwise operator is applied.
If a binary bitwise operator has one long operand, the other operand is converted to a long value.
The type of the result of a bitwise operation is the type to which the operands have been promoted. For example:
short a = 5;
byte b = 10;
long c = 15;
The type of the result of (a+b) is int, not short or byte. The type of the result of (a+c) or (b+c) is long.
Is the numeric promotion available in other platform?
Yes. Because Java is implemented using a platform-independent virtual machine, bitwise operations always yield the same result, even when run on machines that use radically different CPUs.
What is the difference between the Boolean & operator and the && operator?
If an expression involving the Boolean & operator is evaluated, both operands are evaluated. Then the & operator is applied to the operand. When an expression involving the && operator is evaluated, the first operand is evaluated. If the first operand returns a value of true then the second operand is evaluated. The && operator is then applied to the first and second operands. If the first operand evaluates to false, the evaluation of the second operand is skipped.
Operator & has no chance to skip both sides evaluation and && operator does. If asked why, give details as above.
When is the ArithmeticException throwQuestion: What is the GregorianCalendar class?
The GregorianCalendar provides support for traditional Western calendars.
What is the SimpleTimeZone class?
The SimpleTimeZone class provides support for a Gregorian calendar.
How can a subclass call a method or a constructor defined in a superclass?
Use the following syntax: super.myMethod(); To call a constructor of the superclass, just write super(); in the first line of the subclass's constructor.
What is the Properties class?
The properties class is a subclass of Hashtable that can be read from or written to a stream. It also provides the capability to specify a set of default values to be used.
What is the purpose of the Runtime class?
The purpose of the Runtime class is to provide access to the Java runtime system.

What is the purpose of the System class?
The purpose of the System class is to provide access to system resources.
What is the purpose of the finally clause of a try-catch-finally statement?
The finally clause is used to provide the capability to execute code no matter whether or not an exception is thrown or caught.
What is the Locale class?
The Locale class is used to tailor program output to the conventions of a particular geographic, political, or cultural region.
What is an abstract method?
An abstract method is a method whose implementation is deferred to a subclass. Or, a method that has no implementation.
What is the difference between interface and abstract class?
interface contains methods that must be abstract; abstract class may contain concrete methods. interface contains variables that must be static and final; abstract class may contain non-final and final variables. members in an interface are public by default, abstract class may contain non-public members. interface is used to "implements"; whereas abstract class is used to "extends". interface can be used to achieve multiple inheritance; abstract class can be used as a single inheritance. interface can "extends" another interface, abstract class can "extends" another class and "implements" multiple interfaces. interface is absolutely abstract; abstract class can be invoked if a main() exists. interface is more flexible than abstract class because one class can only "extends" one super class, but "implements" multiple interfaces. If given a choice, use interface instead of abstract class.
What is a static method?
A static method is a method that belongs to the class rather than any object of the class and doesn't apply to an object or even require that any objects of the class have been instantiated.
What is a protected method?
A protected method is a method that can be accessed by any method in its package and inherited by any subclass of its class.
What is the difference between a static and a non-static inner class?
A non-static inner class may have object instances that are associated with instances of the class's outer class. A static inner class does not have any object instances.

What is an object's lock and which object's have locks?
An object's lock is a mechanism that is used by multiple threads to obtain synchronized access to the object. A thread may execute a synchronized method of an object only after it has acquired the object's lock. All objects and classes have locks. A class's lock is acquired on the class's Class object.

When can an object reference be cast to an interface reference?
An object reference can be cast to an interface reference when the object implements the referenced interface.
What is the difference between a Window and a Frame?
The Frame class extends Window to define a main application window that can have a menu bar.
What is the difference between a Window and a Frame?
Heavy weight components like Abstract Window Toolkit (AWT), depend on the local windowing toolkit. For example, java.awt.Button is a heavy weight component, when it is running on the Java platform for Unix platform, it maps to a real Motif button. In this relationship, the Motif button is called the peer to the java.awt.Button. If you create two Buttons, two peers and hence two Motif Buttons are also created. The Java platform communicates with the Motif Buttons using the Java Native Interface. For each and every component added to the application, there is an additional overhead tied to the local windowing system, which is why these components are called heavy weight.
Which package has light weight components?
javax.Swing package. All components in Swing, except JApplet, JDialog, JFrame and JWindow are lightweight components.
What are peerless components?
The peerless components are called light weight components.
What is the difference between the Font and FontMetrics classes?
The FontMetrics class is used to define implementation-specific properties, such as ascent and descent, of a Font object

What is the difference between the Reader/Writer class hierarchy and the InputStream/OutputStream class hierarchy?
The Reader/Writer class hierarchy is character-oriented, and the InputStream/OutputStream class hierarchy is byte-oriented.
What classes of exceptions may be caught by a catch clause?
A catch clause can catch any exception that may be assigned to the Throwable type. This includes the Error and Exception types.
What is the difference between throw and throws keywords?
The throw keyword denotes a statement that causes an exception to be initiated. It takes the Exception object to be thrown as argument. The exception will be caught by an immediately encompassing try-catch construction or propagated further up the calling hierarchy.
The throws keyword is a modifier of a method that designates that exceptions may come out of the method, either by virtue of the method throwing the exception itself or because it fails to catch such exceptions that a method it calls may throw.
If a class is declared without any access modifiers, where may the class be accessed?
A class that is declared without any access modifiers is said to have package or friendly access. This means that the class can only be accessed by other classes and interfaces that are defined within the same package.
What is the Map interface?
The Map interface replaces the JDK 1.1 Dictionary class and is used associate keys with values.
Does a class inherit the constructors of its super class?
A class does not inherit constructors from any of its superclasses.
Name primitive Java types.
The primitive types are byte, char, short, int, long, float, double, and Boolean.
Which class should you use to obtain design information about an object?
The Class class is used to obtain information about an object's design.
How can a GUI component handle its own events?
A component can handle its own events by implementing the required event-listener interface and adding itself as its own event listener.
How are the elements of a GridBagLayout organized?
The elements of a GridBagLayout are organized according to a grid. However, the elements are of different sizes and may occupy more than one row or column of the grid. In addition, the rows and columns may have different sizes.
What advantage do Java's layout managers provide over traditional windowing systems?
Java uses layout managers to lay out components in a consistent manner across all windowing platforms. Since Java's layout managers aren't tied to absolute sizing and positioning, they are able to accommodate platform-specific differences among windowing systems.
What are the problems faced by Java programmers who don't use layout managers?
Without layout managers, Java programmers are faced with determining how their GUI will be displayed across multiple windowing systems and finding a common sizing and positioning that will work within the constraints imposed by each windowing system.
What is the difference between static and non-static variables?
A static variable is associated with the class as a whole rather than with specific instances of a class. Non-static variables take on unique values with each object instance.
What is the difference between the paint() and repaint() methods?
The paint() method supports painting via a Graphics object. The repaint() method is used to cause paint() to be invoked by the AWT painting thread.
What is the purpose of the File class?
The File class is used to create objects that provide access to the files and directories of a local file system.
Why would you use a synchronized block vs. synchronized method?
Synchronized blocks place locks for shorter periods than synchronized methods.

What restrictions are placed on method overriding?
Overridden methods must have the same name, argument list, and return type. The overriding method may not limit the access of the method it overrides. The overriding method may not throw any exceptions that may not be thrown by the overridden method.
What is casting?
There are two types of casting, casting between primitive numeric types and casting between object references. Casting between numeric types is used to convert larger values, such as double values, to smaller values, such as byte values. Casting between object references is used to refer to an object by a compatible class, interface, or array type reference.
Explain the usage of the keyword transient?
This keyword indicates that the value of this member variable does not have to be serialized with the object. When the class will be de-serialized, this variable will be initialized with a default value of its data type (i.e. zero for integers).
What class allows you to read objects directly from a stream?
The ObjectInputStream class supports the reading of objects from input streams.
How are this() and super() used with constructors?
this() is used to invoke a constructor of the same class. super() is used to invoke a superclass constructor.

How is it possible for two String objects with identical values not to be equal under the == operator? How are this() and super() used with constructors?
The == operator compares two objects to determine if they are the same objects in memory. It is possible for two String objects to have the same value, but located in different areas of memory.

What is an IO filter?
An IO filter is an object that reads from one stream and writes to another, usually altering the data in some way as it is passed from one stream to another.
What is the Set interface?
The Set interface provides methods for accessing the elements of a finite mathematical set. Sets do not allow duplicate elements.
How can you force garbage collection?
You can't force GC, but could request it by calling System.gc(). JVM does not guarantee that GC will be started immediately.
What is the purpose of the enableEvents() method?
The enableEvents() method is used to enable an event for a particular object. Normally, an event is enabled when a listener is added to an object for a particular event. The enableEvents() method is used by objects that handle events by overriding their event-dispatch methods.
What is the difference between the File and RandomAccessFile classes?
The File class encapsulates the files and directories of the local file system. The RandomAccessFile class provides the methods needed to directly access data contained in any part of a file.
What interface must an object implement before it can be written to a stream as an object?
An object must implement the Serializable or Externalizable interface before it can be written to a stream as an object.
What is the ResourceBundle class?
The ResourceBundle class is used to store locale-specific resources that can be loaded by a program to tailor the program's appearance to the particular locale in which it is being run.
How do you know if an explicit object casting is needed?
If you assign a superclass object to a variable of a subclass's data type, you need to do explicit casting. For example:
Object a; Customer b; b = (Customer) a;
When you assign a subclass to a variable having a supeclass type, the casting is performed automatically.
What is a Java package and how is it used?
A Java package is a naming context for classes and interfaces. A package is used to create a separate name space for groups of classes and interfaces. Packages are also used to organize related classes and interfaces into a single API unit and to control accessibility to these classes and interfaces.
How do you restrict a user to cut and paste from the html page?
Using Servlet or client side scripts to lock keyboard keys. It is one of solutions.

· How could Java classes direct program messages to the system console, but error messages, say to a file?

The class System has a variable out that represents the standard output, and the variable err that represents the standard error device. By default, they both point at the system console. This how the standard output could be re-directed:

Stream st =   new Stream(new FileOutputStream("techinterviews_com.txt")); System.setErr(st);

System.setOut(st);

· What's the difference between an interface and an abstract class?

An abstract class may contain code in method bodies, which is not allowed in an interface. With abstract classes, you have to inherit your class from it and Java does not allow multiple inheritance. On the other hand, you can implement multiple interfaces in your class.

· Why would you use a synchronized block vs. synchronized method?

Synchronized blocks place locks for shorter periods than synchronized methods.

· Explain the usage of the keyword transient?

This keyword indicates that the value of this member variable does not have to be serialized with the object. When the class will be de-serialized, this variable will be initialized with a default value of its data type (i.e. zero for integers).

· How can you force garbage collection?

You can't force GC, but could request it by calling System.gc(). JVM does not guarantee that GC will be started immediately.

· How do you know if an explicit object casting is needed?

If you assign a superclass object to a variable of a subclass's data type, you need to do explicit casting. For example:

Object a;Customer b; b = (Customer) a;

When you assign a subclass to a variable having a supeclass type, the casting is performed automatically.

· What's the difference between the methods sleep() and wait()

The code sleep(1000); puts thread aside for exactly one second. The code wait(1000), causes a wait of up to one second. A thread could stop waiting earlier if it receives the notify() or notifyAll() call. The method wait() is defined in the class Object and the method sleep() is defined in the class Thread.

· Can you write a Java class that could be used both as an applet as well as an application?

Yes. Add a main() method to the applet.

· What's the difference between constructors and other methods?

Constructors must have the same name as the class and can not return a value. They are only called once while regular methods could be called many times.

· Can you call one constructor from another if a class has multiple constructors

Yes. Use this() syntax.

· Explain the usage of Java packages.

This is a way to organize files when a project consists of multiple modules. It also helps resolve naming conflicts when different packages have classes with the same names. Packages access level also allows you to protect data from being used by the non-authorized classes.

· If a class is located in a package, what do you need to change in the OS environment to be able to use it?

· What's the difference between J2SDK 1.5 and J2SDK 5.0?

There's no difference, Sun Microsystems just re-branded this version.

· What would you use to compare two String variables - the operator == or the method equals()?

I'd use the method equals() to compare the values of the Strings and the = = to check if two variables point at the same instance of a String object.

· Does it matter in what order catch statements for FileNotFoundException and IOExceptipon are written?

A. Yes, it does. The FileNoFoundException is inherited from the IOException. Exception's subclasses have to be caught first.

· Can an inner class declared inside of a method access local variables of this method?

It's possible if these variables are final.

· What can go wrong if you replace && with & in the following code:

String a=null;

if (a!=null && a.length()&gt;10)

{...}

A single ampersand here would lead to a NullPointerException.

· What's the main difference between a Vector and an ArrayList

Java Vector class is internally synchronized and ArrayList is not.

· When should the method invokeLater()be used?

This method is used to ensure that Swing components are updated through the event-dispatching thread.

· How can a subclass call a method or a constructor defined in a superclass?

Use the following syntax: super.myMethod(); To call a constructor of the superclass, just write super(); in the first line of the subclass's constructor.

· What's the difference between a queue and a stack?

Stacks works by last-in-first-out rule (LIFO), while queues use the FIFO rule.

· You can create an abstract class that contains only abstract methods. On the other hand, you can create an interface that declares the same methods. So can you use abstract classes instead of interfaces?

Sometimes. But your class may be a descendent of another class and in this case the interface is your only option.

· What comes to mind when you hear about a young generation in Java?

Garbage collection.

· What comes to mind when someone mentions a shallow copy in Java?

Object cloning.

· If you're overriding the method equals() of an object, which other method you might also consider?

hashCode()

· You are planning to do an indexed search in a list of objects. Which of the two Java collections should you use: ArrayList or LinkedList?

ArrayList

· How would you make a copy of an entire Java object with its state?

Have this class implement Cloneable interface and call its method clone().

· How can you minimize the need of garbage collection and make the memory use more effective?

Use object pooling and weak object references.

· There are two classes: A and B. The class B need to inform a class A when some important event has happened. What Java technique would you use to implement it?

If these classes are threads I'd consider notify() or notifyAll(). For regular classes you can use the Observer interface.

· What access level do you need to specify in the class declaration to ensure that only classes from the same directory can access it?

You do not need to specify any access level, and Java will use a default package access level.

What are the Object and Class classes used for?
The Object class is the highest-level class in the Java class hierarchy. The Class class is used to represent the classes and interfaces that are loaded by a Java program.
What is Serialization and deserialization ?
Serialization is the process of writing the state of an object to a byte stream. Deserialization is the process of restoring these objects.
Explain the usage of Java packages.
This is a way to organize files when a project consists of multiple modules. It also helps resolve naming conflicts when different packages have classes with the same names. Packages access level also allows you to protect data from being used by the non-authorized classes.
Does the code in finally block get executed if there is an exception and a return statement in a catch block?
If an exception occurs and there is a return statement in catch block, the finally block is still executed. The finally block will not be executed when the System.exit(1) statement is executed earlier or the system shut down earlier or the memory is used up earlier before the thread goes to finally block.
Is Java a super set of JavaScript?
No. They are completely different. Some syntax may be similar.
What is a Container in a GUI?
A Container contains and arranges other components (including other containers) through the use of layout managers, which use specific layout policies to determine where components should go as a function of the size of the container.
How the object oriented approach helps us keep complexity of software development under control?
We can discuss such issue from the following aspects:
Objects allow procedures to be encapsulated with their data to reduce potential interference.
Inheritance allows well-tested procedures to be reused and enables changes to make once and have effect in all relevant places.
The well-defined separations of interface and implementation allow constraints to be imposed on inheriting classes while still allowing the flexibility of overriding and overloading.
What is polymorphism?
Polymorphism means "having many forms". It allows methods (may be variables) to be written that needn't be concerned about the specifics of the objects they will be applied to. That is, the method can be specified at a higher level of abstraction and can be counted on to work even on objects of un-conceived classes.
What is design by contract?
The design by contract specifies the obligations of a method to any other methods that may use its services and also theirs to it. For example, the preconditions specify what the method required to be true when the method is called. Hence making sure that preconditions are. Similarly, postconditions specify what must be true when the method is finished, thus the called method has the responsibility of satisfying the post conditions.
In Java, the exception handling facilities support the use of design by contract, especially in the case of checked exceptions. The assert keyword can be used to make such contracts.
What are use cases?
A use case describes a situation that a program might encounter and what behavior the program should exhibit in that circumstance. It is part of the analysis of a program. The collection of use cases should, ideally, anticipate all the standard circumstances and many of the extraordinary circumstances possible so that the program will be robust.
What is scalability and performance?
Performance is a measure of "how fast can you perform this task." and scalability describes how an application behaves as its workload and available computing resources increase.
What is the benefit of subclass?
Generally: The sub class inherits all the public methods and the implementation.
The sub class inherits all the protected methods and their implementation.
The sub class inherits all the default(non-access modifier) methods and their implementation.
The sub class also inherits all the public, protected and default member variables from the super class.
The constructors are not part of this inheritance model.
How to add menushortcut to menu item?
If you have a button instance called aboutButton, you may add menu short cut by calling aboutButton.setMnemonic('A'), so the user may be able to use Alt+A to click the button.

In System.out.println(),what is System,out and println,pls explain?
System is a predefined final class,out is a PrintStream object acting as a field member and println is a built-in overloaded method in the out object.
Can you write a Java class that could be used both as an applet as well as an application?
A. Yes. Add a main() method to the applet.
Can you make an instance of an abstract class? For example - java.util.Calender is an abstract class with a method getInstance() which returns an instance of the Calender class.
No! You cannot make an instance of an abstract class. An abstract class has to be sub-classed. If you have an abstract class and you want to use a method which has been implemented, you may need to subclass that abstract class, instantiate your subclass and then call that method.
What is the output of x > y? a:b = p*q when x=1,y=2,p=3,q=4?
When this kind of question has been asked, find the problems you think is necessary to ask back before you give an answer. Ask if variables a and b have been declared or initialized. If the answer is yes. You can say that the syntax is wrong. If the statement is rewritten as: x
What is the difference between Swing and AWT components?
AWT components are heavy-weight, whereas Swing components are lightweight. Heavy weight components depend on the local windowing toolkit. For example, java.awt.Button is a heavy weight component, when it is running on the Java platform for Unix platform, it maps to a real Motif button.
Why Java does not support pointers?
Because pointers are unsafe. Java uses reference types to hide pointers and programmers feel easier to deal with reference types without pointers. This is why Java and C-sharp shine.
Parsers? DOM vs SAX parser
Parsers are fundamental xml components, a bridge between XML documents and applications that process that XML. The parser is responsible for handling xml syntax, checking the contents of the document against constraints established in a DTD or Schema.
DOM
1. Tree of nodes
2. Memory: Occupies more memory, preffered for small XML documents
3. Slower at runtime
4. Stored as objects
5. Programmatically easy
6. Ease of navigation
SAX
1. Sequence of events
2. Doesn't use any memory preferred for large documents
3. Faster at runtime
4. Objects are to be created
5. Need to write code for creating objects
6. Backward navigation is not possible as it sequentially processes the document
Can you declare a class as private?
Yes, we can declare a private class as an inner class. For example,

class MyPrivate {
private static class MyKey {
String key = "12345";
}
public static void main(String[] args) {
System.out.println(new MyKey().key);//prints 12345
}
}
What is the difference between shallow copy and deep copy?
Shallow copy shares the same reference with the original object like cloning, whereas the deep copy get a duplicate instance of the original object. If the shallow copy has been changed, the original object will be reflected and vice versa.
Can one create a method which gets a String and modifies it?
No. In Java, Strings are constant or immutable; their values cannot be changed after they are created, but they can be shared. Once you change a string, you actually create a new object. For example:
String s = "abc"; //create a new String object representing "abc"
s = s.toUpperCase(); //create another object representing "ABC"
Why is multiple inheritance not possible in Java?
It depends on how you understand "inheritance". Java can only "extends" one super class, but can "implements" many interfaces; that doesn't mean the multiple inheritance is not possible. You may use interfaces to make inheritance work for you. Or you may need to work around. For example, if you cannot get a feature from a class because your class has a super class already, you may get that class's feature by declaring it as a member field or getting an instance of that class. So the answer is that multiple inheritance in Java is possible.
What's the difference between constructors and other methods?
Constructors must have the same name as the class and can not return a value. They are only called once while regular methods could be called many times.

What is the relationship between synchronized and volatile keyword?
The JVM is guaranteed to treat reads and writes of data of 32 bits or less as atomic.(Some JVM might treat reads and writes of data of 64 bits or less as atomic in future) For long or double variable, programmers should take care in multi-threading environment. Either put these variables in a synchronized method or block, or declare them volatile.
This class (IncrementImpl) will be used by various threads concurrently; can you see the inherent flaw(s)? How would you improve it?
public class IncrementImpl {
private static int counter = 0;
public synchronized void increment() {
counter++;
}
public int getCounter() {
return counter;
}
}

The counter is static variable which is shared by multiple instances of this class. The increment() method is synchronized, but the getCounter() should be synchronized too. Otherwise the Java run-time system will not guarantee the data integrity and the race conditions will occur. The famous producer/consumer example listed at Sun's thread tutorial site will tell more.
one of solutions
public class IncrementImpl {
private static int counter = 0;
public synchronized void increment() {
counter++;
}
public synchronized int getCounter() {
return counter;
}
}

What are the drawbacks of inheritance?
Since inheritance inherits everything from the super class and interface, it may make the subclass too clustering and sometimes error-prone when dynamic overriding or dynamic overloading in some situation. In addition, the inheritance may make peers hardly understand your code if they don't know how your super-class acts and add learning curve to the process of development.
Usually, when you want to use a functionality of a class, you may use subclass to inherit such function or use an instance of this class in your class. Which is better, depends on your specification.

Is there any other way that you can achieve inheritance in Java?
There are a couple of ways. As you know, the straight way is to "extends" and/or "implements". The other way is to get an instance of the class to achieve the inheritance. That means to make the supposed-super-class be a field member. When you use an instance of the class, actually you get every function available from this class, but you may lose the dynamic features of OOP
Two methods have key words static synchronized and synchronized separately. What is the difference between them?
Both are synchronized methods. One is instance method, the other is class method. Method with static modifier is a class method. That means the method belongs to class itself and can be accessed directly with class name and is also called Singleton design. The method without static modifier is an instance method. That means the instance method belongs to its object. Every instance of the class gets its own copy of its instance method.
When synchronized is used with a static method, a lock for the entire class is obtained. When synchronized is used with a non-static method, a lock for the particular object (that means instance) of the class is obtained.
Since both methods are synchronized methods, you are not asked to explain what is a synchronized method. You are asked to tell the difference between instance and class method. Of course, your explanation to how synchronized keyword works doesn't hurt. And you may use this opportunity to show your knowledge scope.
How do you create a read-only collection?
The Collections class has six methods to help out here:
1. unmodifiableCollection(Collection c)
2. unmodifiableList(List list)
3. unmodifiableMap(Map m)
4. unmodifiableSet(Set s)
5. unmodifiableSortedMap(SortedMap m)
6. unmodifiableSortedSet(SortedSet s)
If you get an Iterator from one of these unmodifiable collections, when you call remove(), it will throw an UnsupportedOperationException.
Can a private method of a superclass be declared within a subclass?
Sure. A private field or method or inner class belongs to its declared class and hides from its subclasses. There is no way for private stuff to have a runtime overloading or overriding (polymorphism) features.
Why Java does not support multiple inheritance ?
This is a classic question. Yes or No depends on how you look at Java. If you focus on the syntax of "extends" and compare with C++, you may answer 'No' and give explanation to support you. Or you may answer 'Yes'. Recommend you to say 'Yes'.
Java DOES support multiple inheritance via interface implementation. Some people may not think in this way. Give explanation to support your point.

What is the difference between final, finally and finalize?
Short answer:
final - declares constant
finally - relates with exception handling
finalize - helps in garbage collection
If asked to give details, explain:
final field, final method, final class
try/finally, try/catch/finally
protected void finalize() in Object class
What kind of security tools are available in J2SE 5.0?
There are three tools that can be used to protect application working within the scope of security policies set at remote sites.
keytool -- used to manage keystores and certificates.
jarsigner -- used to generate and verify JAR signatures.
policytool -- used for managing policy files.
There are three tools that help obtain, list and manage Kerberos tickets.
kinit -- used to obtain Kerberos V5 tickets.
tklist -- used to list entries in credential cache and key tab.
ktab -- used to help manage entries in the key table.
How to make an array copy from System?
There is a method called arraycopy in the System class. You can do it:
System.arraycopy(sourceArray, srcOffset, destinationArray, destOffset, numOfElements2Copy);
When you use this method, the destinationArray will be filled with the elements of sourceArray at the length specified.
Can we use System.arraycopy() method to copy the same array?
Yes, you can. The source and destination arrays can be the same if you want to copy a subset of the array to another area within that array.
What is shallow copy or shallow clone in array cloning?
Cloning an array invloves creating a new array of the same size and type and copying all the old elements into the new array. But such copy is called shallow copy or shallow clone because any changes to the object would be reflected in both arrays.
When is the ArrayStoreException thrown?
When copying elements between different arrays, if the source or destination arguments are not arrays or their types are not compatible, an ArrayStoreException will be thrown.
How to check two arrays to see if contents have the same types and contain the same elements?
One of options is to use the equals() method of Arrays class.
Arrays.equals(a, b);
If the array types are different, a compile-time error will happen.
Can you call one constructor from another if a class has multiple constructors?
Yes. Use this() syntax.
What are the different types of inner classes?
There are four different types of inner classes in Java. They are: a)Static member classes , a static member class has access to all static methods of the parent, or top-level, class b) Member classes, the member class is instance specific and has access to any and all methods and members, even the parent's this reference c) Local classes, are declared within a block of code and are visible only within that block, just as any other method variable. d) Anonymous classes, is a local class that has no name
In which case would you choose a static inner class?
Interesting one, static inner classes can access the outer class's protected and private fields. This is both a positive and a negative point for us since we can, in essence, violate the encapsulation of the outer class by mucking up the outer class's protected and private fields. The only proper use of that capability is to write white-box tests of the class -- since we can induce cases that might be very hard to induce via normal black-box tests (which don't have access to the internal state of the object). Second advantage,if I can say, is that, we can this static concept to impose restriction on the inner class. Again as discussed in earlier point, an Inner class has access to all the public, private and protected members of the parent class. Suppose you want to restrict the access even to inner class, how would you go ahead? Making the inner class static enforces it to access only the public static members of the outer class( Since, protected and private members are not supposed to be static and that static members can access only other static members). If it has to access any non-static member, it has to create an instance of the outer class which leads to accessing only public members.
What is weak reference in Java
A weak reference is one that does not prevent the referenced object from being garbage collected. You might use them to manage a HashMap to look up a cache of objects. A weak reference is a reference that does not keep the object it refers to alive. A weak reference is not counted as a reference in garbage collection. If the object is not referred to elsewhere as well, it will be garbage collected.

What is the difference between final, finally and finalize?
final is used for making a class no-subclassable, and making a member variable as a constant which cannot be modified. finally is usually used to release all the resources utilized inside the try block. All the resources present in the finalize method will be garbage collected whenever GC is called. Though finally and finalize seem to be for a similar task there is an interesting tweak here, usually I prefer finally than finalize unless it is unavoidable. This is because the code in finally block is guaranteed of execution irrespective of occurrence of exception, while execution of finalize is not guarenteed.finalize method is called by the garbage collector on an object when the garbage collector determines that there are no more references to the object. Presumably the garbage collector will, like its civil servant namesake, visit the heap on a regular basis to clean up resources that are no longer in use. Garbage collection exists to prevent programmers from calling delete. This is a wonderful feature. For example, if you can't call delete, then you can't accidentally call delete twice on the same object. However, removing delete from the language is not the same thing as automatically cleaning up. To add to it, Garbage collection might not ever run. If garbage collection runs at all, and an object is no longer referenced, then that object's finalize will run. Also, across multiple objects, finalize order is not predictable. The correct approach to resource cleanup in Java language programs does not rely on finalize. Instead, you simply write explicit close methods for objects that wrap native resources. If you take this approach, you must document that the close method exists and when it should be called. Callers of the object must then remember to call close when they are finished with a resource.
What's the difference between the methods sleep() and wait()
The code sleep(1000); puts thread aside for exactly one second. The code wait(1000), causes a wait of up to one second. A thread could stop waiting earlier if it receives the notify() or notifyAll() call. The method wait() is defined in the class Object and the method sleep() is defined in the class Thread.
The following statement prints true or false, why?
byte[] a = { 1, 2, 3 };,
byte[] b = (byte[]) a.clone();
System.out.println(a == b);
The false will be printed out. Because the two arrays have distinctive memory addresses. Starting in Java 1.2, we can use java.util.Arrays.equals(a, b) to compare whether two arrays have the same contents.
Why do we need to use getSystemResource() and getSystemResources() method to load resources?
Because we want to look for resources strictly from the system classpath, These methods use the system ClassLoader to locate resources, which gives you stricter control of the resources used by the application.
ArithmeticException?
The ArithmeticException is thrown when integer is divided by zero or taking the remainder of a number by zero. It is never thrown in floating-point operations.
What is a transient variable?
A transient variable is a variable that may not be serialized.
Which containers use a border Layout as their default layout?
The window, Frame and Dialog classes use a border layout as their default layout.
Why do threads block on I/O?
Threads block on I/O (that is enters the waiting state) so that other threads may execute while the I/O Operation is performed.
What is the output from System.out.println("Hello"+null);?
Hellonull
What is synchronization and why is it important?
With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources. Without synchronization, it is possible for one thread to modify a shared object while another thread is in the process of using or updating that object's value. This often leads to significant errors.
Can a lock be acquired on a class?
Yes, a lock can be acquired on a class. This lock is acquired on the class's Class object.
What's new with the stop(), suspend() and resume() methods in JDK 1.2?
The stop(), suspend() and resume() methods have been deprecated in JDK 1.2.
Is null a keyword?
The null value is not a keyword.
What is the preferred size of a component?
The preferred size of a component is the minimum component size that will allow the component to display normally.

What method is used to specify a container's layout?
The setLayout() method is used to specify a container's layout.
Which containers use a FlowLayout as their default layout?
The Panel and Applet classes use the FlowLayout as their default layout.

What state does a thread enter when it terminates its processing?
When a thread terminates its processing, it enters the dead state.

What is the Collections API?
The Collections API is a set of classes and interfaces that support operations on collections of objects.
Which characters may be used as the second character of an identifier, but not as the first character of an identifier?
The digits 0 through 9 may not be used as the first character of an identifier but they may be used after the first character of an identifier.
What is the List interface?
The List interface provides support for ordered collections of objects.

How does Java handle integer overflows and underflows?
It uses those low order bytes of the result that can fit into the size of the type allowed by the operation.

What is the Vector class?
The Vector class provides the capability to implement a growable array of objects
What modifiers may be used with an inner class that is a member of an outer class?
A (non-local) inner class may be declared as public, protected, private, static, final, or abstract.
What is an Iterator interface?
The Iterator interface is used to step through the elements of a Collection.
What is the difference between the >> and >>> operators?
The >> operator carries the sign bit when shifting right. The >>> zero-fills bits that have been shifted out.
Which method of the Component class is used to set the position and size of a component?
setBounds()
How many bits are used to represent Unicode, ASCII, UTF-16, and UTF-8 characters?
Unicode requires 16 bits and ASCII require 7 bits. Although the ASCII character set uses only 7 bits, it is usually represented as 8 bits. UTF-8 represents characters using 8, 16, and 18 bit patterns. UTF-16 uses 16-bit and larger bit patterns.
What is the difference between yielding and sleeping?
When a task invokes its yield() method, it returns to the ready state. When a task invokes its sleep() method, it returns to the waiting state.
Which java.util classes and interfaces support event handling?
The EventObject class and the EventListener interface support event processing.
Is sizeof a keyword?
The sizeof operator is not a keyword.
What are wrapper classes?
Wrapper classes are classes that allow primitive types to be accessed as objects.
Does garbage collection guarantee that a program will not run out of memory?
Garbage collection does not guarantee that a program will not run out of memory. It is possible for programs to use up memory resources faster than they are garbage collected. It is also possible for programs to create objects that are not subject to garbage collection.
What restrictions are placed on the location of a package statement within a source code file?
A package statement must appear as the first line in a source code file (excluding blank lines and comments).

Can an object's finalize() method be invoked while it is reachable?
An object's finalize() method cannot be invoked by the garbage collector while the object is still reachable. However, an object's finalize() method may be invoked by other objects.
What is the immediate superclass of the Applet class?
Panel

What is the difference between preemptive scheduling and time slicing?
Under preemptive scheduling, the highest priority task executes until it enters the waiting or dead states or a higher priority task comes into existence. Under time slicing, a task executes for a predefined slice of time and then reenters the pool of ready tasks. The scheduler then determines which task should execute next, based on priority and other factors.

Name three Component subclasses that support painting.
The Canvas, Frame, Panel, and Applet classes support painting.
What value does readLine() return when it has reached the end of a file?
The readLine() method returns null when it has reached the end of a file.

What is the immediate superclass of the Dialog class?
Window.

What is clipping?
Clipping is the process of confining paint operations to a limited area or shape.
What is a native method?
A native method is a method that is implemented in a language other than Java.
Can a for statement loop indefinitely?
Yes, a for statement can loop indefinitely. For example, consider the following: for(;;) ;
What are order of precedence and associativity, and how are they used?
Order of precedence determines the order in which operators are evaluated in expressions. Associatity determines whether an expression is evaluated left-to-right or right-to-left
When a thread blocks on I/O, what state does it enter?
A thread enters the waiting state when it blocks on I/O.
To what value is a variable of the String type automatically initialized?
The default value of a String type is null.
What is the catch or declare rule for method declarations?
If a checked exception may be thrown within the body of a method, the method must either catch the exception or declare it in its throws clause.
What is the difference between a MenuItem and a CheckboxMenuItem?
The CheckboxMenuItem class extends the MenuItem class to support a menu item that may be checked or unchecked.
What is a task's priority and how is it used in scheduling?
A task's priority is an integer value that identifies the relative order in which it should be executed with respect to other tasks. The scheduler attempts to schedule higher priority tasks before lower priority tasks.
What class is the top of the AWT event hierarchy?
The java.awt.AWTEvent class is the highest-level class in the AWT event-class hierarchy.
When a thread is created and started, what is its initial state?
A thread is in the ready state after it has been created and started.
Can an anonymous class be declared as implementing an interface and extending a class?
An anonymous class may implement an interface or extend a superclass, but may not be declared to do both.

What is the range of the short type?
The range of the short type is -(2^15) to 2^15 - 1.
What is the range of the char type?
The range of the char type is 0 to 2^16 - 1.

In which package are most of the AWT events that support the event-delegation model defined?
Most of the AWT-related events of the event-delegation model are defined in the java.awt.event package. The AWTEvent class is defined in the java.awt package.

What is the immediate super class of Menu?
What is the immediate super class of Menu? MenuItem
What is the purpose of finalization?
The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup processing before the object is garbage collected.
Which class is the immediate super class of the MenuComponent class.
Object

What invokes a thread's run() method?
After a thread is started, via its start() method or that of the Thread class, the JVM invokes the thread's run() method when the thread is initially executed.

What is the difference between the Boolean & operator and the && operator?
If an expression involving the Boolean & operator is evaluated, both operands are evaluated. Then the & operator is applied to the operand. When an expression involving the && operator is evaluated, the first operand is evaluated. If the first operand returns a value of true then the second operand is evaluated. The && operator is then applied to the first and second operands. If the first operand evaluates to false, the evaluation of the second operand is skipped.
Name three subclasses of the Component class.
Box.Filler, Button, Canvas, Checkbox, Choice, Container, Label, List, Scrollbar, or TextComponent
What is the GregorianCalendar class?
The GregorianCalendar provides support for traditional Western calendars.
Which Container method is used to cause a container to be laid out and redisplayed?
validate()
What is the purpose of the Runtime class?
The purpose of the Runtime class is to provide access to the Java runtime system.
How many times may an object's finalize() method be invoked by the garbage collector?
An object's finalize() method may only be invoked once by the garbage collector.
What is the purpose of the finally clause of a try-catch-finally statement? garbage collector?
The finally clause is used to provide the capability to execute code no matter whether or not an exception is thrown or caught.
What is the argument type of a program's main() method?
A program's main() method takes an argument of the String[] type.
Which Java operator is right associative?
The = operator is right associative.
What is the Locale class?
The Locale class is used to tailor program output to the conventions of a particular geographic, political, or cultural region.
Can a double value be cast to a byte?
Yes, a double value can be cast to a byte.

What is the difference between a break statement and a continue statement?
A break statement results in the termination of the statement to which it applies (switch, for, do, or while). A continue statement is used to end the current loop iteration and return control to the loop statement.
What must a class do to implement an interface?
It must provide all of the methods in the interface and identify the interface in its implements clause.
What method is invoked to cause an object to begin executing as a separate thread?
The start() method of the Thread class is invoked to cause an object to begin executing as a separate thread.
Name two subclasses of the TextComponent class.
TextField and TextArea
What is the advantage of the event-delegation model over the earlier event-inheritance model?
The event-delegation model has two advantages over the event-inheritance model. First, it enables event handling to be handled by objects other than the ones that generate the events (or their containers). This allows a clean separation between a component's design and its use. The other advantage of the event-delegation model is that it performs much better in applications where many events are generated. This performance improvement is due to the fact that the event-delegation model does not have to repeatedly process unhandled events, as is the case of the event-inheritance model.
Which containers may have a MenuBar?
Frame
How are commas used in the initialization and iteration parts of a for statement?
Commas are used to separate multiple statements within the initialization and iteration parts of a for statement.
What is the purpose of the wait(), notify(), and notifyAll() methods?
The wait(),notify(), and notifyAll() methods are used to provide an efficient way for threads to wait for a shared resource. When a thread executes an object's wait() method, it enters the waiting state. It only enters the ready state after another thread invokes the object's notify() or notifyAll() methods.

What is an abstract method?
An abstract method is a method whose implementation is deferred to a subclass.

How are Java source code files named?
A Java source code file takes the name of a public class or interface that is defined within the file. A source code file may contain at most one public class or interface. If a public class or interface is defined within a source code file, then the source code file must take the name of the public class or interface. If no public class or interface is defined within a source code file, then the file must take on a name that is different than its classes and interfaces. Source code files use the .java extension.
What is the relationship between the Canvas class and the Graphics class?
A Canvas object provides access to a Graphics object via its paint() method.
What are the high-level thread states?
The high-level thread states are ready, running, waiting, and dead.
What value does read() return when it has reached the end of a file?
The read() method returns -1 when it has reached the end of a file.
Can a Byte object be cast to a double value?
No, an object cannot be cast to a primitive value.
What is the difference between a static and a non-static inner class?
A non-static inner class may have object instances that are associated with instances of the class's outer class. A static inner class does not have any object instances.
What is the difference between the String and StringBuffer classes?
String objects are constants. StringBuffer objects are not.
If a variable is declared as private, where may the variable be accessed?
A private variable may only be accessed within the class in which it is declared.

What is an object's lock and which objects have locks?
An object's lock is a mechanism that is used by multiple threads to obtain synchronized access to the object. A thread may execute a synchronized method of an object only after it has acquired the object's lock. All objects and classes have locks. A class's lock is acquired on the class's Class object.
What is the Dictionary class?
The Dictionary class provides the capability to store key-value pairs.
How are the elements of a BorderLayout organized?
The elements of a BorderLayout are organized at the borders (North, South, East, and West) and the center of a container.
What is the % operator?
It is referred to as the modulo or remainder operator. It returns the remainder of dividing the first operand by the second operand.
When can an object reference be cast to an interface reference?
An object reference be cast to an interface reference when the object implements the referenced interface.
What is the difference between a Window and a Frame?
The Frame class extends Window to define a main application window that can have a menu bar.
Which class is extended by all other classes?
The Object class is extended by all other classes.
Can an object be garbage collected while it is still reachable?
A reachable object cannot be garbage collected. Only unreachable objects may be garbage collected..
Is the ternary operator written x : y ? z or x ? y : z ?
It is written x ? y : z.
What is the difference between the Font and FontMetrics classes?
The FontMetrics class is used to define implementation-specific properties, such as ascent and descent, of a Font object.
How is rounding performed under integer division?
The fractional part of the result is truncated. This is known as rounding toward zero.
What happens when a thread cannot acquire a lock on an object?
If a thread attempts to execute a synchronized method or synchronized statement and is unable to acquire an object's lock, it enters the waiting state until the lock becomes available.
What is the difference between the Reader/Writer class hierarchy and the InputStream/OutputStream class hierarchy?
The Reader/Writer class hierarchy is character-oriented, and the InputStream/OutputStream class hierarchy is byte-oriented.
What classes of exceptions may be caught by a catch clause?
A catch clause can catch any exception that may be assigned to the Throwable type. This includes the Error and Exception types.
If a class is declared without any access modifiers, where may the class be accessed?
A class that is declared without any access modifiers is said to have package access. This means that the class can only be accessed by other classes and interfaces that are defined within the same package.
What is the SimpleTimeZone class?
The SimpleTimeZone class provides support for a Gregorian calendar.
What is the Map interface?
The Map interface replaces the JDK 1.1 Dictionary class and is used associate keys with values.

Does a class inherit the constructors of its superclass?
A class does not inherit constructors from any of its super classes.

For which statements does it make sense to use a label?
The only statements for which it makes sense to use a label are those statements that can enclose a break or continue statement.
What is the purpose of the System class?
The purpose of the System class is to provide access to system resources.
Which TextComponent method is used to set a TextComponent to the read-only state?
setEditable()
How are the elements of a CardLayout organized?
The elements of a CardLayout are stacked, one on top of the other, like a deck of cards.
Is &&= a valid Java operator?
No, it is not.
Name the eight primitive Java types.
The eight primitive types are byte, char, short, int, long, float, double, and boolean.
Which class should you use to obtain design information about an object?
The Class class is used to obtain information about an object's design.
What is the relationship between clipping and repainting?
When a window is repainted by the AWT painting thread, it sets the clipping regions to the area of the window that requires repainting.
Is "abc" a primitive value?
The String literal "abc" is not a primitive value. It is a String object.
What is the relationship between an event-listener interface and an event-adapter class?
An event-listener interface defines the methods that must be implemented by an event handler for a particular kind of event. An event adapter provides a default implementation of an event-listener interface.
What restrictions are placed on the values of each case of a switch statement?
During compilation, the values of each case of a switch statement must evaluate to a value that can be promoted to an int value.
What modifiers may be used with an interface declaration?
An interface may be declared as public or abstract.
Is a class a subclass of itself?
A class is a subclass of itself.
What is the highest-level event class of the event-delegation model?
The java.util.EventObject class is the highest-level class in the event-delegation class hierarchy.
What event results from the clicking of a button?
The ActionEvent event is generated as the result of the clicking of a button.
How can a GUI component handle its own events?
A component can handle its own events by implementing the required event-listener interface and adding itself as its own event listener.
What is the difference between a while statement and a do statement?
A while statement checks at the beginning of a loop to see whether the next loop iteration should occur. A do statement checks at the end of a loop to see whether the next iteration of a loop should occur. The do statement will always execute the body of a loop at least once.
How are the elements of a GridBagLayout organized?
The elements of a GridBagLayout are organized according to a grid. However, the elements are of different sizes and may occupy more than one row or column of the grid. In addition, the rows and columns may have different sizes.

What advantage do Java's layout managers provide over traditional windowing systems?
Java uses layout managers to lay out components in a consistent manner across all windowing platforms. Since Java's layout managers aren't tied to absolute sizing and positioning, they are able to accommodate platform-specific differences among windowing systems.
What is the Collection interface?
The Collection interface provides support for the implementation of a mathematical bag - an unordered collection of objects that may contain duplicates.
What modifiers can be used with a local inner class?
A local inner class may be final or abstract.
What is the difference between static and non-static variables?
A static variable is associated with the class as a whole rather than with specific instances of a class. Non-static variables take on unique values with each object instance.
What is the difference between the paint() and repaint() methods?
The paint() method supports painting via a Graphics object. The repaint() method is used to cause paint() to be invoked by the AWT painting thread.
What is the purpose of the File class?
The File class is used to create objects that provide access to the files and directories of a local file system.
Can an exception be rethrown?
Yes, an exception can be rethrown.
Which Math method is used to calculate the absolute value of a number?
The abs() method is used to calculate absolute values.
How does multithreading take place on a computer with a single CPU?
The operating system's task scheduler allocates execution time to multiple tasks. By quickly switching between executing tasks, it creates the impression that tasks execute sequentially.
When does the compiler supply a default constructor for a class?
The compiler supplies a default constructor for a class if no other constructors are provided.
When is the finally clause of a try-catch-finally statement executed?
The finally clause of the try-catch-finally statement is always executed unless the thread of execution terminates or an exception occurs within the execution of the finally clause.
Which class is the immediate superclass of the Container class?
Component
If a method is declared as protected, where may the method be accessed?
A protected method may only be accessed by classes or interfaces of the same package or by subclasses of the class in which it is declared.
How can the Checkbox class be used to create a radio button?
By associating Checkbox objects with a CheckboxGroup.
Which non-Unicode letter characters may be used as the first character of an identifier?
The non-Unicode letter characters $ and _ may appear as the first character of an identifier
What restrictions are placed on method overloading?
Two methods may not have the same name and argument list but different return types.
What happens when you invoke a thread's interrupt method while it is sleeping or waiting?
When a task's interrupt() method is executed, the task enters the ready state. The next time the task enters the running state, an InterruptedException is thrown.
What is the return type of a program's main() method?
A program's main() method has a void return type.

Name four Container classes.
Window, Frame, Dialog, FileDialog, Panel, Applet, or ScrollPane
What is the difference between a Choice and a List?
A Choice is displayed in a compact form that requires you to pull it down to see the list of available choices. Only one item may be selected from a Choice. A List may be displayed in such a way that several List items are visible. A List supports the selection of one or more List items.
What class of exceptions are generated by the Java run-time system?
The Java runtime system generates RuntimeException and Error exceptions.
What class allows you to read objects directly from a stream?
The ObjectInputStream class supports the reading of objects from input streams.
What is the difference between a field variable and a local variable?
A field variable is a variable that is declared as a member of a class. A local variable is a variable that is declared local to a method.
Under what conditions is an object's finalize() method invoked by the garbage collector?
The garbage collector invokes an object's finalize() method when it detects that the object has become unreachable.
How are this () and super () used with constructors?
this() is used to invoke a constructor of the same class. super() is used to invoke a superclass constructor.
What is the relationship between a method's throws clause and the exceptions that can be thrown during the method's execution?
A method's throws clause must declare any checked exceptions that are not caught within the body of the method.
What is the difference between the JDK 1.02 event model and the event-delegation model introduced with JDK 1.1?
The JDK 1.02 event model uses an event inheritance or bubbling approach. In this model, components are required to handle their own events. If they do not handle a particular event, the event is inherited by (or bubbled up to) the component's container. The container then either handles the event or it is bubbled up to its container and so on, until the highest-level container has been tried. In the event-delegation model, specific objects are designated as event handlers for GUI components. These objects implement event-listener interfaces. The event-delegation model is more efficient than the event-inheritance model because it eliminates the processing required to support the bubbling of unhandled events.
How is it possible for two String objects with identical values not to be equal under the == operator?
The == operator compares two objects to determine if they are the same object in memory. It is possible for two String objects to have the same value, but located indifferent areas of memory.
Why are the methods of the Math class static?
So they can be invoked as if they are a mathematical code library.
What Checkbox method allows you to tell if a Checkbox is checked?
getState()
What state is a thread in when it is executing?
An executing thread is in the running state.
What are the legal operands of the instanceof operator?
The left operand is an object reference or null value and the right operand is a class, interface, or array type.
How are the elements of a GridLayout organized?
The elements of a GridBad layout are of equal size and are laid out using the squares of a grid.
What an I/O filter?
An I/O filter is an object that reads from one stream and writes to another, usually altering the data in some way as it is passed from one stream to another.
If an object is garbage collected, can it become reachable again?
Once an object is garbage collected, it ceases to exist. It can no longer become reachable again.

What are E and PI?
E is the base of the natural logarithm and PI is mathematical value pi.
Are true and false keywords?
The values true and false are not keywords.
What is a void return type?
A void return type indicates that a method does not return a value.
What is the purpose of the enableEvents() method?
The enableEvents() method is used to enable an event for a particular object. Normally, an event is enabled when a listener is added to an object for a particular event. The enableEvents() method is used by objects that handle events by overriding their event-dispatch methods.
What is the difference between the File and RandomAccessFile classes?
The File class encapsulates the files and directories of the local file system. The RandomAccessFile class provides the methods needed to directly access data contained in any part of a file.
What happens when you add a double value to a String?
The result is a String object.
What is your platform's default character encoding?
If you are running Java on English Windows platforms, it is probably Cp1252. If you are running Java on English Solaris platforms, it is most likely 8859_1..
Which package is always imported by default?
The java.lang package is always imported by default.
What interface must an object implement before it can be written to a stream as an object?
An object must implement the Serializable or Externalizable interface before it can be written to a stream as an object.
How are this and super used?
this is used to refer to the current object instance. super is used to refer to the variables and methods of the superclass of the current object instance.
What is the purpose of garbage collection?
The purpose of garbage collection is to identify and discard objects that are no longer needed by a program so that their resources may be reclaimed and reused.
What is a compilation unit?
A compilation unit is a Java source code file.
What interface is extended by AWT event listeners?
All AWT event listeners extend the java.util.EventListener interface.
What restrictions are placed on method overriding?
Overridden methods must have the same name, argument list, and return type. The overriding method may not limit the access of the method it overrides. The overriding method may not throw any exceptions that may not be thrown by the overridden method.
How can a dead thread be restarted?
A dead thread cannot be restarted.
What happens if an exception is not caught?
An uncaught exception results in the uncaughtException() method of the thread's ThreadGroup being invoked, which eventually results in the termination of the program in which it is thrown.
What is a layout manager?
A layout manager is an object that is used to organize components in a container.
Which arithmetic operations can result in the throwing of an ArithmeticException?
Integer / and % can result in the throwing of an ArithmeticException.

What are three ways in which a thread can enter the waiting state?
A thread can enter the waiting state by invoking its sleep() method, by blocking on I/O, by unsuccessfully attempting to acquire an object's lock, or by invoking an object's wait() method. It can also enter the waiting state by invoking its (deprecated) suspend() method.
Can an abstract class be final?
An abstract class may not be declared as final.
What is the ResourceBundle class?
The ResourceBundle class is used to store locale-specific resources that can be loaded by a program to tailor the program's appearance to the particular locale in which it is being run.
What happens if a try-catch-finally statement does not have a catch clause to handle an exception that is thrown within the body of the try statement?
The exception propagates up to the next higher level try-catch statement (if any) or results in the program's termination.
What is numeric promotion?
Numeric promotion is the conversion of a smaller numeric type to a larger numeric type, so that integer and floating-point operations may take place. In numerical promotion, byte, char, and short values are converted to int values. The int values are also converted to long values, if necessary. The long and float values are converted to double values, as required.
What is the difference between a Scrollbar and a ScrollPane?
A Scrollbar is a Component, but not a Container. A ScrollPane is a Container. A ScrollPane handles its own events and performs its own scrolling.
What is the difference between a public and a non-public class?
A public class may be accessed outside of its package. A non-public class may not be accessed outside of its package.
To what value is a variable of the boolean type automatically initialized?
The default value of the boolean type is false.
Can try statements be nested?
Try statements may be tested.
What is the difference between the prefix and postfix forms of the ++ operator?
The prefix form performs the increment operation and returns the value of the increment operation. The postfix form returns the current value all of the expression and then performs the increment operation on that value.
What is the purpose of a statement block?
A statement block is used to organize a sequence of statements as a single statement group.
What is a Java package and how is it used?
A Java package is a naming context for classes and interfaces. A package is used to create a separate name space for groups of classes and interfaces. Packages are also used to organize related classes and interfaces into a single API unit and to control accessibility to these classes and interfaces.
What modifiers may be used with a top-level class?
A top-level class may be public, abstract, or final.
What are the Object and Class classes used for?
The Object class is the highest-level class in the Java class hierarchy. The Class class is used to represent the classes and interfaces that are loaded by a Java program.
How does a try statement determine which catch clause should be used to handle an exception?
When an exception is thrown within the body of a try statement, the catch clauses of the try statement are examined in the order in which they appear. The first catch clause that is capable of handling the exception is executed. The remaining catch clauses are ignored.
Can an unreachable object become reachable again?
An unreachable object may become reachable again. This can happen when the object's finalize() method is invoked and the object performs an operation which causes it to become accessible to reachable objects.

When is an object subject to garbage collection?
An object is subject to garbage collection when it becomes unreachable to the program in which it is used.
What method must be implemented by all threads?
All tasks must implement the run() method, whether they are a subclass of Thread or implement the Runnable interface.
What methods are used to get and set the text label displayed by a Button object?
getLabel() and setLabel()
Which Component subclass is used for drawing and painting?
Canvas
What are the two basic ways in which classes that can be run as threads may be defined?
A thread class may be declared as a subclass of Thread, or it may implement the Runnable interface.
What are the problems faced by Java programmers who don't use layout managers?
Without layout managers, Java programmers are faced with determining how their GUI will be displayed across multiple windowing systems and finding a common sizing and positioning that will work within the constraints imposed by each windowing system.
What is the difference between an if statement and a switch statement?
The if statement is used to select among two alternatives. It uses a Boolean expression to decide which alternative should be executed. The switch statement is used to select among multiple alternatives. It uses an int expression to determine which alternative should be executed.
Can there be an abstract class with no abstract methods in it?
yes.
Can an Interface be final?
yes.
Can an Interface have an inner class?
Yes public interface abc { static int i=0; void dd(); class a1 { a1() { int j; System.out.println("in interfia"); }; public static void main(String a1[]) { System.out.println("in interfia"); } } }
Can we define private and protected modifiers for variables in interfaces?
Yes.
What is Externalizable?
Externalizable is an Interface that extends Serializable Interface. And sends data into Streams in Compressed Format. It has two methods, writeExternal(ObjectOuput out) and readExternal(ObjectInput in)
What modifiers are allowed for methods in an Interface?
Only public and abstract modifiers are allowed for methods in interfaces.
What is a local, member and a class variable?
Variables declared within a method are "local" variables.
Variables declared within the class i.e not within any methods are "member" variables (global variables).
Variables declared within the class i.e not within any methods and are defined as "static" are class variables
I made my class Cloneable but I still get 'Can't access protected method clone. Why?
Yeah, some of the Java books, in particular "The Java Programming Language", imply that all you have to do in order to have your class support clone() is implement the Cloneable interface. Not so. Perhaps that was the intent at some point, but that's not the way it works currently. As it stands, you have to implement your own public clone() method, even if it doesn't do anything special and just calls super.clone().
What are the different identifier states of a Thread?
The different identifiers of a Thread are:
R - Running or runnable thread
S - Suspended thread
CW - Thread waiting on a condition variable
MW - Thread waiting on a monitor lock
MS - Thread suspended waiting on a monitor lock

What are some alternatives to inheritance?
Delegation is an alternative to inheritance. Delegation means that you include an instance of another class as an instance variable, and forward messages to the instance. It is often safer than inheritance because it forces you to think about each message you forward, because the instance is of a known class, rather than a new class, and because it doesn't force you to accept all the methods of the super class: you can provide only the methods that really make sense. On the other hand, it makes you write more code, and it is harder to re-use (because it is not a subclass).
Why isn't there operator overloading?
Because C++ has proven by example that operator overloading makes code almost impossible to maintain. In fact there very nearly wasn't even method overloading in Java, but it was thought that this was too useful for some very basic methods like print(). Note that some of the classes like DataOutputStream have unoverloaded methods like writeInt() and writeByte().
What does it mean that a method or field is "static"?
Static variables and methods are instantiated only once per class. In other words they are class variables, not instance variables. If you change the value of a static variable in a particular object, the value of that variable changes for all instances of that class.
Static methods can be referenced with the name of the class rather than the name of a particular object of the class (though that works too). That's how library methods like System.out.println() work. out is a static field in the java.lang.System class.
Why do threads block on I/O?
Threads block on i/o (that is enters the waiting state) so that other threads may execute while the i/o Operation is performed.
What is synchronization and why is it important?
With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources. Without synchronization, it is possible for one thread to modify a shared object while another thread is in the process of using or updating that object's value. This often leads to significant errors.
Is null a keyword?
The null value is not a keyword.
Which characters may be used as the second character of an identifier,but not as the first character of an identifier?
The digits 0 through 9 may not be used as the first character of an identifier but they may be used after the first character of an identifier.
What is the difference between notify() and notifyAll()?
notify() is used to unblock one waiting thread; notifyAll() is used to unblock all of them. Using notify() is preferable (for efficiency) when only one blocked thread can benefit from the change (for example, when freeing a buffer back into a pool). notifyAll() is necessary (for correctness) if multiple threads should resume (for example, when releasing a "writer" lock on a file might permit all "readers" to resume).
Why can't I say just abs() or sin() instead of Math.abs() and Math.sin()?
The import statement does not bring methods into your local name space. It lets you abbreviate class names, but not get rid of them altogether. That's just the way it works, you'll get used to it. It's really a lot safer this way.
However, there is actually a little trick you can use in some cases that gets you what you want. If your top-level class doesn't need to inherit from anything else, make it inherit from java.lang.Math. That *does* bring all the methods into your local name space. But you can't use this trick in an applet, because you have to inherit from java.awt.Applet. And actually, you can't use it on java.lang.Math at all, because Math is a "final" class which means it can't be extended.
Why are there no global variables in Java?
Global variables are considered bad form for a variety of reasons: · Adding state variables breaks referential transparency (you no longer can understand a statement or expression on its own: you need to understand it in the context of the settings of the global variables).
· State variables lessen the cohesion of a program: you need to know more to understand how something works. A major point of Object-Oriented programming is to break up global state into more easily understood collections of local state.
· When you add one variable, you limit the use of your program to one instance. What you thought was global, someone else might think of as local: they may want to run two copies of your program at once.
For these reasons, Java decided to ban global variables.
What does it mean that a class or member is final?
A final class can no longer be subclassed. Mostly this is done for security reasons with basic classes like String and Integer. It also allows the compiler to make some optimizations, and makes thread safety a little easier to achieve. Methods may be declared final as well. This means they may not be overridden in a subclass.
Fields can be declared final, too. However, this has a completely different meaning. A final field cannot be changed after it's initialized, and it must include an initializer statement where it's declared. For example,
public final double c = 2.998;
It's also possible to make a static field final to get the effect of C++'s const statement or some uses of C's #define, e.g. public static final double c = 2.998;

What does it mean that a method or class is abstract?
An abstract class cannot be instantiated. Only its subclasses can be instantiated. You indicate that a class is abstract with the abstract keyword like this:
public abstract class Container extends Component {
Abstract classes may contain abstract methods. A method declared abstract is not actually implemented in the current class. It exists only to be overridden in subclasses. It has no body. For example,
public abstract float price();
Abstract methods may only be included in abstract classes. However, an abstract class is not required to have any abstract methods, though most of them do.
Each subclass of an abstract class must override the abstract methods of its superclasses or itself be declared abstract.
What is the main difference between Java platform and other platforms?
The Java platform differs from most other platforms in that it's a software-only platform that runs on top of other hardware-based platforms.
The Java platform has three elements:
Java programming language
The Java Virtual Machine (Java VM)
The Java Application Programming Interface (Java API)
What is the Java Virtual Machine?
The Java Virtual Machine is a software that can be ported onto various hardware-based platforms.
What is the Java API?
The Java API is a large collection of ready-made software components that provide many useful capabilities, such as graphical user interface (GUI) widgets.
What is the package?
The package is a Java namespace or part of Java libraries. The Java API is grouped into libraries of related classes and interfaces; these libraries are known as packages.
What is native code?
The native code is code that after you compile it, the compiled code runs on a specific hardware platform.
Explain the user defined Exceptions?
User defined Exceptions are the separate Exception classes defined by the user for specific purposed. An user defined can created by simply sub-classing it to the Exception class. This allows custom exceptions to be generated (using throw) and caught in the same way as normal exceptions.
Example:
class myCustomException extends Exception {
// The class simply has to exist to be an exception
}
Is Java code slower than native code?
Not really. As a platform-independent environment, the Java platform can be a bit slower than native code. However, smart compilers, well-tuned interpreters, and just-in-time bytecode compilers can bring performance close to that of native code without threatening portability.
Can main() method be overloaded?
Yes. the main() method is a special method for a program entry. You can overload main() method in any ways. But if you change the signature of the main method, the entry point for the program will be gone.
What is the serialization?
The serialization is a kind of mechanism that makes a class or a bean persistence by having its properties or fields and state information saved and restored to and from storage.
Explain the new Features of JDBC 2.0 Core API?
The JDBC 2.0 API includes the complete JDBC API, which includes both core and Optional Package API, and provides inductrial-strength database computing capabilities.
New Features in JDBC 2.0 Core API:

Scrollable result sets- using new methods in the ResultSet interface allows programmatically move the to particular row or to a position relative to its current position
JDBC 2.0 Core API provides the Batch Updates functionality to the java applications.
Java applications can now use the ResultSet.updateXXX methods.
New data types - interfaces mapping the SQL3 data types
Custom mapping of user-defined types (UTDs)
Miscellaneous features, including performance hints, the use of character streams, full precision for java.math.BigDecimal values, additional security, and support for time zones in date, time, and timestamp values.
How you can force the garbage collection?
Garbage collection automatic process and can't be forced.

Explain garbage collection?
Garbage collection is one of the most important feature of Java. Garbage collection is also called automatic memory management as JVM automatically removes the unused variables/objects (value is null) from the memory. User program cann't directly free the object from memory, instead it is the job of the garbage collector to automatically free the objects that are no longer referenced by a program. Every class inherits finalize() method from java.lang.Object, the finalize() method is called by garbage collector when it determines no more references to the object exists. In Java, it is good idea to explicitly assign null into a variable when no more in use. I Java on calling System.gc() and Runtime.gc(), JVM tries to recycle the unused objects, but there is no guarantee when all the objects will garbage collected.
Describe the principles of OOPS.
There are three main principals of oops which are called Polymorphism, Inheritance and Encapsulation.
Explain the Encapsulation principle.
Encapsulation is a process of binding or wrapping the data and the codes that operates on the data into a single entity. This keeps the data safe from outside interface and misuse. One way to think about encapsulation is as a protective wrapper that prevents code and data from being arbitrarily accessed by other code defined outside the wrapper.
Explain the Inheritance principle.
Inheritance is the process by which one object acquires the properties of another object.
Explain the Polymorphism principle.
The meaning of Polymorphism is something like one name many forms. Polymorphism enables one entity to be used as as general category for different types of actions. The specific action is determined by the exact nature of the situation. The concept of polymorphism can be explained as "one interface, multiple methods".
Explain the different forms of Polymorphism.
From a practical programming viewpoint, polymorphism exists in three distinct forms in Java:
Method overloading
Method overriding through inheritance
Method overriding through the Java interface
What are Access Specifiers available in Java?
ccess specifiers are keywords that determines the type of access to the member of a class. These are:
Public
Protected
Private
Defaults
Describe the wrapper classes in Java.
Wrapper class is wrapper around a primitive data type. An instance of a wrapper class contains, or wraps, a primitive value of the corresponding type.

Following table lists the primitive types and the corresponding wrapper classes:

Primitive Wrapper
boolean java.lang.Boolean
byte java.lang.Byte
char java.lang.Character
double java.lang.Double
float java.lang.Float
int java.lang.Integer
long java.lang.Long
short java.lang.Short
void java.lang.Void
Question: Read the following program:
public class test {
public static void main(String [] args) {
int x = 3;
int y = 1;
if (x = y)
System.out.println("Not equal");
else
System.out.println("Equal");
}
}

What is the result?
A. The output is "Equal"
B. The output in "Not Equal"
C. An error at " if (x = y)" causes compilation to fall.
D. The program executes but no output is show on console.

Answer: C
Use the Externalizable interface when you need complete control over your Bean's serialization (for example, when writing and reading a specific file format).
No. Earlier order is maintained.

he superclass constructor runs before the subclass constructor. The subclass's version of the overridable method will be invoked before the subclass's constructor has been invoked. If the subclass's overridable method depends on the proper initialization of the subclass (through the subclass constructor), the method will most likely fail. Is that true?
Yes. It is true
Why are the interfaces more flexible than abstract classes?
--An interface-defined type can be implemented by any class in a class hierarchy and can be extended by another interface. In contrast, an abstract-class-defined type can be implemented only by classes that subclass the abstract class.
--An interface-defined type can be used well in polymorphism. The so-called interface type vs. implementation types.
--Abstract classes evolve more easily than interfaces. If you add a new concrete method to an abstract class, the hierarchy system is still working. If you add a method to an interface, the classes that rely on the interface will break when recompiled.
--Generally, use interfaces for flexibility; use abstract classes for ease of evolution (like expanding class functionality).
What are new language features in J2SE 5.0?
Generally:
1. generics
2. static imports
3. annotations
4. typesafe enums
5. enhanced for loop
6. autoboxing/unboxing
7. varargs
8. covariant return types
What is covariant return type?
A covariant return type lets you override a superclass method with a return type that subtypes the superclass method's return type. So we can use covariant return types to minimize upcasting and downcasting.
class Parent {
Parent foo () {
System.out.println ("Parent foo() called");
return this;
}
}

class Child extends Parent {
Child foo () {
System.out.println ("Child foo() called");
return this;
}
}

class Covariant {
public static void main(String[] args) {
Child c = new Child();
Child c2 = c.foo(); // c2 is Child
Parent c3 = c.foo(); // c3 points to Child
}
}
What is the result of the following statement?
int i = 1, float f = 2.0f;
i += f; //ok, the cast done automatically by the compiler
i = i + f; //error
The compound assignment operators automatically include cast operations in their behaviors.
What is externalization? Where is it useful?
Use the Externalizable interface when you need complete control over your Bean's serialization (for example, when writing and reading a specific file format).
What will be the output on executing the following code.
public class MyClass {
public static void main (String args[] ) {
int abc[] = new int [5];
System.out.println(abc);
}
}

A Error array not initialized
B 5
C null
D Print some junk characters

Answer : D

It will print some junk characters to the output. Here it will not give any compile time or runtime error because we have declared and initialized the array properly. Event if we are not assigning a value to the array, it will always initialized to its defaults.
What will be the output on executing the following code.
public class MyClass {
public static void main (String args[] ) {
int abc[] = new int [5];
System.out.println(abc[0]);
}
}
A Error array not initialized
B 5
C 0
D Print some junk characters

Answer : C.

What is a marker interface ?
An interface that contains no methods. E.g.: Serializable, Cloneable, SingleThreadModel etc. It is used to just mark java classes that support certain capability.
What are tag interfaces?
Tag interface is an alternate name for marker interface.
What are the restrictions placed on static method ?
We cannot override static methods. We cannot access any object variables inside static method. Also the this reference also not available in static methods.
What is JVM?
JVM stands for Java Virtual Machine. It is the run time for java programs. All are java programs are running inside this JVM only. It converts java byte code to OS specific commands. In addition to governing the execution of an application's byte codes, the virtual machine handles related tasks such as managing the system's memory, providing security against malicious code, and managing multiple threads of program execution.
What is JIT?
JIT stands for Just In Time compiler. It compiles java byte code to native code.
What are ClassLoaders?
A class loader is an object that is responsible for loading classes. The class ClassLoader is an abstract class. Given the name of a class, a class loader should attempt to locate or generate data that constitutes a definition for the class. A typical strategy is to transform the name into a file name and then read a "class file" of that name from a file system.
Every Class object contains a reference to the ClassLoader that defined it.
Class objects for array classes are not created by class loaders, but are created automatically as required by the Java runtime. The class loader for an array class, as returned by Class.getClassLoader() is the same as the class loader for its element type; if the element type is a primitive type, then the array class has no class loader.
Applications implement subclasses of ClassLoader in order to extend the manner in which the Java virtual machine dynamically loads classes.
What is Service Locator pattern?
The Service Locator pattern locates J2EE (Java 2 Platform, Enterprise Edition) services for clients and thus abstracts the complexity of network operation and J2EE service lookup as EJB (Enterprise JavaBean) Interview Questions - Home and JMS (Java Message Service) component factories. The Service Locator hides the lookup process's implementation details and complexity from clients. To improve application performance, Service Locator caches service objects to eliminate unnecessary JNDI (Java Naming and Directory Interface) activity that occurs in a lookup operation.
What is Session Facade pattern?
Session facade is one design pattern that is often used while developing enterprise applications. It is implemented as a higher level component (i.e.: Session EJB), and it contains all the iteractions between low level components (i.e.: Entity EJB). It then provides a single interface for the functionality of an application or part of it, and it decouples lower level components simplifying the design. Think of a bank situation, where you have someone that would like to transfer money from one account to another. In this type of scenario, the client has to check that the user is authorized, get the status of the two accounts, check that there are enough money on the first one, and then call the transfer. The entire transfer has to be done in a single transaction otherwise is something goes south, the situation has to be restored.
As you can see, multiple server-side objects need to be accessed and possibly modified. Multiple fine-grained invocations of Entity (or even Session) Beans add the overhead of network calls, even multiple transaction. In other words, the risk is to have a solution that has a high network overhead, high coupling, poor reusability and mantainability.
The best solution is then to wrap all the calls inside a Session Bean, so the clients will have a single point to access (that is the session bean) that will take care of handling all the rest.
What is Data Access Object pattern?
The Data Access Object (or DAO) pattern: separates a data resource's client interface from its data access mechanisms adapts a specific data resource's access API to a generic client interface
The DAO pattern allows data access mechanisms to change independently of the code that uses the data.
The DAO implements the access mechanism required to work with the data source. The data source could be a persistent store like an RDBMS, an external service like a B2B exchange, a repository like an LDAP database, or a business service accessed via CORBA Internet Inter-ORB Protocol (IIOP) or low-level sockets. The business component that relies on the DAO uses the simpler interface exposed by the DAO for its clients. The DAO completely hides the data source implementation details from its clients. Because the interface exposed by the DAO to clients does not change when the underlying data source implementation changes, this pattern allows the DAO to adapt to different storage schemes without affecting its clients or business components. Essentially, the DAO acts as an adapter between the component and the data source.
Can we make an EJB singleton?
This is a debatable question, and for every answer we propose there can be contradictions. I propose 2 solutions of the same. Remember that EJB's are distributed components and can be deployed on different JVM's in a Distributed environment
i) Follow the steps as given below
Make sure that your serviceLocator is deployed on only one JVM.
In the serviceLocator create a HashTable/HashMap(You are the right judge to choose between these two)
When ever a request comes for an EJB to a serviceLocator, it first checks in the HashTable if an entry already exists in the table with key being the JNDI name of EJB. If key is present and value is not null, return the existing reference, else lookup the EJB in JNDI as we do normally and add an entry into the Hashtable before returning it to the client. This makes sure that you maintain a singleton of EJB.
ii) In distributed environment our components/Java Objects would be running on different JVM's. So the normal singleton code we write for maintaining single instance works fine for single JVM, but when the class could be loaded in multiple JVM's and Instantiated in multiple JVM's normal singleton code does not work. This is because the ClassLoaders being used in the different JVM's are different from each other and there is no defined mechanism to check and compare what is loaded in another JVM. A solution could be(Not tested yet. Need your feedback on this) to write our own ClassLoader and pass this classLoader as argument, whenever we are creating a new Instance and make sure that only one instance is created for the proposed class. This can be done easily.

How can we make a class Singleton ?
A) If the class is Serializable

class Singleton implements Serializable
{
private static Singleton instance;

private Singleton() { }

public static synchronized Singleton getInstance()
{
if (instance == null)
instance = new Singleton();
return instance;
}

/**
If the singleton implements Serializable, then this
* method must be supplied.
*/
protected Object readResolve() {
return instance;
}

/**
This method avoids the object fro being cloned
*/
public Object clone() {
throws CloneNotSupportedException ;
//return instance;
}
}

B) If the class is NOT Serializable

class Singleton
{
private static Singleton instance;
private Singleton() { }

public static synchronized Singleton getInstance()
{
if (instance == null)
instance = new Singleton();
return instance;
}

/**
This method avoids the object from being cloned
**/
public Object clone() {
throws CloneNotSupportedException ;
//return instance;
}

}
How is static Synchronization different form non-static synchronization?
When Synchronization is applied on a static Member or a static block, the lock is performed on the Class and not on the Object, while in the case of a Non-static block/member, lock is applied on the Object and not on class. [Trail 2: There is a class called Class in Java whose object is associated with the object(s) of your class. All the static members declared in your class will have reference in this class(Class). As long as your class exists in memory this object of Class is also present. Thats how even if you create multiple objects of your class only one Class object is present and all your objects are linked to this Class object. Even though one of your object is GCed after some time, this object of Class is not GCed untill all the objects associated with it are GCed.
This means that when ever you call a "static synchronized" block, JVM locks access to this Class object and not any of your objects. Your client can till access the non-static members of your objects.
What are class members and Instance members?
Any global members(Variables, methods etc.) which are static are called as Class level members and those which are non-static are called as Instance level members.
Name few Garbage collection algorithms?
Here they go:
Mark and Sweep
Reference counting
Tracing collectors
Copying collectors
Heap compaction
Mark-compact collectors
Can we force Garbage collection?
java follows a philosophy of automatic garbage collection, you can suggest or encourage the JVM to perform garbage collection but you can not force it. Once a variable is no longer referenced by anything it is available for garbage collection. You can suggest garbage collection with System.gc(), but this does not guarantee when it will happen. Local variables in methods go out of scope when the method exits. At this point the methods are eligible for garbage collection. Each time the method comes into scope the local variables are re-created.

Does Java pass by Value or reference?
Its uses Reference while manipulating objects but pass by value when sending method arguments. Those who feel why I added this simple question in this section while claiming to be maintaining only strong and interesting questions, go ahead and answer following questions.
a)What is the out put of:

import java.util.*;

class TestCallByRefWithObject
{
ArrayList list = new ArrayList(5);

public void remove(int index){
list.remove(index);
}

public void add(Object obj){
list.add(obj);
}

public void display(){
System.out.println(list);
}

public static void main(String[] args)
{
TestCallByRefWithObject test = new TestCallByRefWithObject();

test.add("1");
test.add("2");
test.add("3");
test.add("4");
test.add("5");

test.remove(4);
test.display();
}
}

b) And now what is the output of:

import java.util.*;

class TestCallByRefWithInt
{
int i = 5;

public void decrement(int i){
i--;
}

public void increment(int i){
i++;
}

public void display(){
System.out.println("\nValue of i is : " +i);
}

public static void main(String[] args)
{
TestCallByRefWithInt test = new TestCallByRefWithInt();

test.increment(test.i);

test.display();
}
}
Why Thread is faster compare to process?
A thread is never faster than a process. If you run a thread(say there's a process which has spawned only one thread) in one JVM and a process in another and that both of them require same resources then both of them would take same time to execute. But, when a program/Application is thread based(remember here there will be multiple threads running for a single process) then definetly a thread based appliation/program is faster than a process based application. This is because, when ever a process requires or waits for a resource CPU takes it out of the critical section and allocates the mutex to another process.
Before deallocating the ealier one, it stores the context(till what state did it execute that process) in registers. Now if this deallocated process has to come back and execute as it has got the resource for which it was waiting, then it can't go into critical section directly. CPU asks that process to follow scheduling algorithm. So this process has to wait again for its turn. While in the case of thread based application, the application is still with CPU only that thread which requires some resource goes out, but its co threads(of same process/apllication) are still in the critical section. Hence it directly comes back to the CPU and does not wait outside. Hence an application which is thread based is faster than an application which is process based.
Be sure that its not the competion between thread and process, its between an application which is thread based or process based.
When and How is an object considered as Garbage by a GC?
An object is considered garbage when it can no longer be reached from any pointer in the running program. The most straightforward garbage collection algorithms simply iterate over every reachable object. Any objects left over are then considered garbage.

What are generations in Garbage Collection terminology? What is its relevance?
Garbage Collectors make assumptions about how our application runs. Most common assumption is that an object is most likely to die shortly after it was created: called infant mortality. This assumes that an object that has been around for a while, will likely stay around for a while. GC organizes objects into generations (young, tenured, and perm). This tells that if an object lives for more than certain period of time it is moved from one generation to another generations( say from young -> tenured -> permanent). Hence GC will be run more frequently at the young generations and rarely at permanent generations. This reduces the overhead on GC and gives faster response time.
What is a Throughput Collector?
The throughput collector is a generational collector similar to the default collector but with multiple threads used to do the minor collection. The major collections are essentially the same as with the default collector. By default on a host with N CPUs, the throughput collector uses N garbage collector threads in the collection. The number of garbage collector threads can be controlled with a command line option.
When to Use the Throughput Collector?
Use the throughput collector when you want to improve the performance of your application with larger numbers of processors. In the default collector garbage collection is done by one thread, and therefore garbage collection adds to the serial execution time of the application. The throughput collector uses multiple threads to execute a minor collection and so reduces the serial execution time of the application. A typical situation is one in which the application has a large number of threads allocating objects. In such an application it is often the case that a large young generation is needed
What is Aggressive Heap?
The -XX:+AggressiveHeap option inspects the machine resources (size of memory and number of processors) and attempts to set various parameters to be optimal for long-running, memory allocation-intensive jobs. It was originally intended for machines with large amounts of memory and a large number of CPUs, but in the J2SE platform, version 1.4.1 and later it has shown itself to be useful even on four processor machines. With this option the throughput collector (-XX:+UseParallelGC) is used along with adaptive sizing (-XX:+UseAdaptiveSizePolicy). The physical memory on the machines must be at least 256MB before Aggressive Heap can be used.
What is a Concurrent Low Pause Collector?
The concurrent low pause collector is a generational collector similar to the default collector. The tenured generation is collected concurrently with this collector. This collector attempts to reduce the pause times needed to collect the tenured generation. It uses a separate garbage collector thread to do parts of the major collection concurrently with the applications threads. The concurrent collector is enabled with the command line option -XX:+UseConcMarkSweepGC. For each major collection the concurrent collector will pause all the application threads for a brief period at the beginning of the collection and toward the middle of the collection. The second pause tends to be the longer of the two pauses and multiple threads are used to do the collection work during that pause. The remainder of the collection is done with a garbage collector thread that runs concurrently with the application. The minor collections are done in a manner similar to the default collector, and multiple threads can optionally be used to do the minor collection.
When to Use the Concurrent Low Pause Collector?
Use the concurrent low pause collector if your application would benefit from shorter garbage collector pauses and can afford to share processor resources with the garbage collector when the application is running. Typically applications which have a relatively large set of long-lived data (a large tenured generation), and run on machines with two or more processors tend to benefit from the use of this collector. However, this collector should be considered for any application with a low pause time requirement. Optimal results have been observed for interactive applications with tenured generations of a modest size on a single processor.
What is Incremental Low Pause Collector?
The incremental low pause collector is a generational collector similar to the default collector. The minor collections are done with the same young generation collector as the default collector. Do not use either -XX:+UseParallelGC or -XX:+UseParNewGC with this collector. The major collections are done incrementally on the tenured generation. This collector (also known as the train collector) collects portions of the tenured generation at each minor collection. The goal of the incremental collector is to avoid very long major collection pauses by doing portions of the major collection work at each minor collection. The incremental collector will sometimes find that a non-incremental major collection (as is done in the default collector) is required in order to avoid running out of memory.
When to Use the Incremental Low Pause Collector?
Use the incremental low pause collector when your application can afford to trade longer and more frequent young generation garbage collection pauses for shorter tenured generation pauses. A typical situation is one in which a larger tenured generation is required (lots of long-lived objects), a smaller young generation will suffice (most objects are short-lived and don't survive the young generation collection), and only a single processor is available.
How do you enable the concurrent garbage collector on Sun's JVM?
-Xconcgc options allows us to use concurrent garbage collector (1.2.2_07+)we can also use -XX:+UseConcMarkSweepGC which is available beginning with J2SE 1.4.1.
What is a platform?
A platform is the hardware or software environment in which a program runs. Most platforms can be described as a combination of the operating system and hardware, like Windows 2000 and XP, Linux, Solaris, and MacOS.
What is transient variable?
Transient variable can't be serialize. For example if a variable is declared as transient in a Serializable class and the class is written to an ObjectStream, the value of the variable can't be written to the stream instead when the class is retrieved from the ObjectStream the value of the variable becomes null.

How to make a class or a bean serializable?
By implementing either the java.io.Serializable interface, or the java.io.Externalizable interface. As long as one class in a class's inheritance hierarchy implements Serializable or Externalizable, that class is serializable.
What restrictions are placed on method overloading?
Two methods may not have the same name and argument list but different return types.
Name Container classes.
Window, Frame, Dialog, FileDialog, Panel, Applet, or ScrollPane
What is the List interface?
The List interface provides support for ordered collections of objects.
What is the difference between a Scrollbar and a ScrollPane?
A Scrollbar is a Component, but not a Container. A ScrollPane is a Container. A ScrollPane handles its own events and performs its own scrolling.
What is tunnelling?
Tunnelling is a route to somewhere. For example, RMI tunnelling is a way to make RMI application get through firewall. In CS world, tunnelling means a way to transfer data.
What is meant by "Abstract Interface"?
First, an interface is abstract. That means you cannot have any implementation in an interface. All the methods declared in an interface are abstract methods or signatures of the methods.
Can Java code be compiled to machine dependent executable file?
Yes. There are many tools out there. If you did so, the generated exe file would be run in the specific platform, not cross-platform.
Do not use the String contatenation operator in lengthy loops or other places where performance could suffer. Is that true?
Yes.
What method is used to specify a container's layout?
The setLayout() method is used to specify a container's layout.
Which containers use a FlowLayout as their default layout?
The Panel and Applet classes use the FlowLayout as their default layout.
What state does a thread enter when it terminates its processing?
When a thread terminates its processing, it enters the dead state.
What is the Collections API?
The Collections API is a set of classes and interfaces that support operations on collections of objects.
What is the List interface?
The List interface provides support for ordered collections of objects.
Is sizeof a keyword?
The sizeof operator is not a keyword in Java.
Which class is the superclass for every class.
Object.
Which Container method is used to cause a container to be laid out and redisplayed?
validate()
What's the difference between a queue and a stack?
Stacks works by last-in-first-out rule (LIFO), while queues use the FIFO rule
What comes to mind when you hear about a young generation in Java?
Garbage collection.

You can create an abstract class that contains only abstract methods. On the other hand, you can create an interface that declares the same methods. So can you use abstract classes instead of interfaces?
Sometimes. But your class may be a descendent of another class and in this case the interface is your only option.
What comes to mind when someone mentions a shallow copy in Java?
Object cloning.
If you're overriding the method equals() of an object, which other method you might also consider?
hashCode()
You are planning to do an indexed search in a list of objects. Which of the two Java collections should you use: ArrayList or LinkedList?
ArrayList
How would you make a copy of an entire Java object with its state?
Have this class implement Cloneable interface and call its method clone().
How can you minimize the need of garbage collection and make the memory use more effective?
Use object pooling and weak object references.
There are two classes: A and B. The class B need to inform a class A when some important event has happened. What Java technique would you use to implement it?
If these classes are threads I'd consider notify() or notifyAll(). For regular classes you can use the Observer interface.
What access level do you need to specify in the class declaration to ensure that only classes from the same directory can access it?
You do not need to specify any access level, and Java will use a default package access level.
What is the difference between an Interface and an Abstract class?
An abstract class can have instance methods that implement a default behavior. An Interface can only declare constants and instance methods, but cannot implement default behavior and all methods are implicitly abstract. An interface has all public members and no implementation. An abstract class is a class which may have the usual flavors of class members (private, protected, etc.), but has some abstract methods.
What is the purpose of garbage collection in Java, and when is it used?
The purpose of garbage collection is to identify and discard objects that are no longer needed by a program so that their resources can be reclaimed and reused. A Java object is subject to garbage collection when it becomes unreachable to the program in which it is used.
Describe synchronization in respect to multithreading.
With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources. Without synchonization, it is possible for one thread to modify a shared variable while another thread is in the process of using or updating same shared variable. This usually leads to significant errors.
Explain different way of using thread?
The thread could be implemented by using runnable interface or by inheriting from the Thread class. The former is more advantageous, 'cause when you are going for multiple inheritance..the only interface can help.
What are pass by reference and passby value?
Pass By Reference means the passing the address itself rather than passing the value. Passby Value means passing a copy of the value to be passed.
What is HashMap and Map?
Map is Interface and Hashmap is class that implements that.
Difference between HashMap and HashTable?
The HashMap class is roughly equivalent to Hashtable, except that it is unsynchronized and permits nulls. (HashMap allows null values as key and value whereas Hashtable doesnt allow). HashMap does not guarantee that the order of the map will remain constant over time. HashMap is unsynchronized and Hashtable is synchronized.
Difference between Vector and ArrayList?
Vector is synchronized whereas arraylist is not.

Difference between Swing and AWT?
AWT are heavy-weight components. Swings are light-weight components. Hence swing works faster than AWT.
What is the difference between a constructor and a method?
A constructor is a member function of a class that is used to create objects of that class. It has the same name as the class itself, has no return type, and is invoked using the new operator. A method is an ordinary member function of a class. It has its own name, a return type (which may be void), and is invoked using the dot operator.
What is an Iterator?
Some of the collection classes provide traversal of their contents via a java.util.Iterator interface. This interface allows you to walk through a collection of objects, operating on each object in turn. Remember when using Iterators that they contain a snapshot of the collection at the time the Iterator was obtained; generally it is not advisable to modify the collection itself while traversing an Iterator.
State the significance of public, private, protected, default modifiers both singly and in combination and state the effect of package relationships on declared items qualified by these modifiers.
public : Public class is visible in other packages, field is visible everywhere (class must be public too) private : Private variables or methods may be used only by an instance of the same class that declares the variable or method, A private feature may only be accessed by the class that owns the feature. protected : Is available to all classes in the same package and also available to all subclasses of the class that owns the protected feature. This access is provided even to subclasses that reside in a different package from the class that owns the protected feature. default :What you get by default ie, without any access modifier (ie, public private or protected). It means that it is visible to all within a particular package.
What is an abstract class?
Abstract class must be extended/subclassed (to be useful). It serves as a template. A class that is abstract may not be instantiated (ie, you may not call its constructor), abstract class may contain static data. Any class with an abstract method is automatically abstract itself, and must be declared as such.
A class may be declared abstract even if it has no abstract methods. This prevents it from being instantiated.
What is static in java?
Static means one per class, not one for each object no matter how many instance of a class might exist. This means that you can use them without creating an instance of a class. Static methods are implicitly final, because overriding is done based on the type of the object, and static methods are attached to a class, not an object. A static method in a super class can be shadowed by another static method in a subclass, as long as the original method was not declared final. However, you can't override a static method with a no static method. In other words, you can't change a static method into an instance method in a subclass.
What is final?
A final class can't be extended ie., final class may not be subclassed. A final method can't be overridden when its class is inherited. You can't change value of a final variable (is a constant).
What if the main method is declared as private?
The program compiles properly but at runtime it will give "Main method not public." message.
What if the static modifier is removed from the signature of the main method?
Program compiles. But at runtime throws an error "NoSuchMethodError".
What if I write static public void instead of public static void?
Program compiles and runs properly.
What if I do not provide the String array as the argument to the method?
Program compiles but throws a runtime error "NoSuchMethodError".
What is the first argument of the String array in main method?
The String array is empty. It does not have any element. This is unlike C/C++ where the first element by default is the program name.
If I do not provide any arguments on the command line, then the String array of Main method will be empty or null?
It is empty. But not null.
How can one prove that the array is not null but empty using one line of code?
Print args.length. It will print 0. That means it is empty. But if it would have been null then it would have thrown a NullPointerException on attempting to print args.length.

Can an application have multiple classes having main method?
Yes it is possible. While starting the application we mention the class name to be run. The JVM will look for the Main method only in the class whose name you have mentioned. Hence there is not conflict amongst the multiple classes having main method.
Can I have multiple main methods in the same class?
No the program fails to compile. The compiler says that the main method is already defined in the class.
Do I need to import java.lang package any time? Why ?
No. It is by default loaded internally by the JVM.
Can I import same package/class twice? Will the JVM load the package twice at runtime?
One can import the same package or same class multiple times. Neither compiler nor JVM complains abt it. And the JVM will internally load the class only once no matter how many times you import the same class.
What are Checked and UnChecked Exception?
A checked exception is some subclass of Exception (or Exception itself), excluding class RuntimeException and its subclasses. Making an exception checked forces client programmers to deal with the possibility that the exception will be thrown. eg, IOException thrown by java.io.FileInputStream's read() method· Unchecked exceptions are RuntimeException and any of its subclasses. Class Error and its subclasses also are unchecked. With an unchecked exception, however, the compiler doesn't force client programmers either to catch the exception or declare it in a throws clause. In fact, client programmers may not even know that the exception could be thrown. eg, StringIndexOutOfBoundsException thrown by String's charAt() method· Checked exceptions must be caught at compile time. Runtime exceptions do not need to be. Errors often cannot be.
What is Overriding?
When a class defines a method using the same name, return type, and arguments as a method in its superclass, the method in the class overrides the method in the superclass.
When the method is invoked for an object of the class, it is the new definition of the method that is called, and not the method definition from superclass. Methods may be overridden to be more public, not more private.
What are different types of inner classes?
Nested top-level classes, Member classes, Local classes, Anonymous classes

Nested top-level classes- If you declare a class within a class and specify the static modifier, the compiler treats the class just like any other top-level class.
Any class outside the declaring class accesses the nested class with the declaring class name acting similarly to a package. eg, outer.inner. Top-level inner classes implicitly have access only to static variables.There can also be inner interfaces. All of these are of the nested top-level variety.

Member classes - Member inner classes are just like other member methods and member variables and access to the member class is restricted, just like methods and variables. This means a public member class acts similarly to a nested top-level class. The primary difference between member classes and nested top-level classes is that member classes have access to the specific instance of the enclosing class.

Local classes - Local classes are like local variables, specific to a block of code. Their visibility is only within the block of their declaration. In order for the class to be useful beyond the declaration block, it would need to implement a more publicly available interface.Because local classes are not members, the modifiers public, protected, private, and static are not usable.

Anonymous classes - Anonymous inner classes extend local inner classes one level further. As anonymous classes have no name, you cannot provide a constructor.
Are the imports checked for validity at compile time? e.g. will the code containing an import such as java.lang.ABCD compile?
Yes the imports are checked for the semantic validity at compile time. The code containing above line of import will not compile. It will throw an error saying,can not resolve symbol
symbol : class ABCD
location: package io
import java.io.ABCD;
Does importing a package imports the subpackages as well? e.g. Does importing com.MyTest.* also import com.MyTest.UnitTests.*?
No you will have to import the subpackages explicitly. Importing com.MyTest.* will import classes in the package MyTest only. It will not import any class in any of it's subpackage.
What is the difference between declaring a variable and defining a variable?
In declaration we just mention the type of the variable and it's name. We do not initialize it. But defining means declaration + initialization.
e.g String s; is just a declaration while String s = new String ("abcd"); Or String s = "abcd"; are both definitions.
What is the default value of an object reference declared as an instance variable?
Null unless we define it explicitly.

Can a top level class be private or protected?
No. A top level class can not be private or protected. It can have either "public" or no modifier. If it does not have a modifier it is supposed to have a default access.If a top level class is declared as private the compiler will complain that the "modifier private is not allowed here". This means that a top level class can not be private. Same is the case with protected.
What type of parameter passing does Java support?
In Java the arguments are always passed by value .
Primitive data types are passed by reference or pass by value?
Primitive data types are passed by value.
Objects are passed by value or by reference?
Java only supports pass by value. With objects, the object reference itself is passed by value and so both the original reference and parameter copy both refer to the same object .
What is serialization?
Serialization is a mechanism by which you can save the state of an object by converting it to a byte stream.
How do I serialize an object to a file?
The class whose instances are to be serialized should implement an interface Serializable. Then you pass the instance to the ObjectOutputStream which is connected to a fileoutputstream. This will save the object to a file.
Which methods of Serializable interface should I implement?
The serializable interface is an empty interface, it does not contain any methods. So we do not implement any methods.
How can I customize the serialization process? i.e. how can one have a control over the serialization process?
Yes it is possible to have control over serialization process. The class should implement Externalizable interface. This interface contains two methods namely readExternal and writeExternal. You should implement these methods and write the logic for customizing the serialization process.
What is the common usage of serialization?
Whenever an object is to be sent over the network, objects need to be serialized. Moreover if the state of an object is to be saved, objects need to be serilized.
What is Externalizable interface?
Externalizable is an interface which contains two methods readExternal and writeExternal. These methods give you a control over the serialization mechanism. Thus if your class implements this interface, you can customize the serialization process by implementing these methods.
When you serialize an object, what happens to the object references included in the object?
The serialization mechanism generates an object graph for serialization. Thus it determines whether the included object references are serializable or not. This is a recursive process. Thus when an object is serialized, all the included objects are also serialized alongwith the original obect.
What one should take care of while serializing the object?
One should make sure that all the included objects are also serializable. If any of the objects is not serializable then it throws a NotSerializableException.
What happens to the static fields of a class during serialization?
There are three exceptions in which serialization doesnot necessarily read and write to the stream. These are
1. Serialization ignores static fields, because they are not part of ay particular state state.
2. Base class fields are only hendled if the base class itself is serializable.
3. Transient fields.
Does Java provide any construct to find out the size of an object?
No there is not sizeof operator in Java. So there is not direct way to determine the size of an object directly in Java.
What are wrapper classes?
Java provides specialized classes corresponding to each of the primitive data types. These are called wrapper classes. They are e.g. Integer, Character, Double etc

Give a simplest way to find out the time a method takes for execution without using any profiling tool?
Read the system time just before the method is invoked and immediately after method returns. Take the time difference, which will give you the time taken by a method for execution.

To put it in code...
long start = System.currentTimeMillis ();
method ();
long end = System.currentTimeMillis ();

System.out.println ("Time taken for execution is " + (end - start));

Remember that if the time taken for execution is too small, it might show that it is taking zero milliseconds for execution. Try it on a method which is big enough, in the sense the one which is doing considerable amount of processing.
Why do we need wrapper classes?
It is sometimes easier to deal with primitives as objects. Moreover most of the collection classes store objects and not primitive data types. And also the wrapper classes provide many utility methods also. Because of these reasons we need wrapper classes. And since we create instances of these classes we can store them in any of the collection classes and pass them around as a collection. Also we can pass them around as method parameters where a method expects an object.
What are checked exceptions?
Checked exception are those which the Java compiler forces you to catch. e.g. IOException are checked Exceptions.
What are runtime exceptions?
Runtime exceptions are those exceptions that are thrown at runtime because of either wrong input data or because of wrong business logic etc. These are not checked by the compiler at compile time.
What is the difference between error and an exception?
An error is an irrecoverable condition occurring at runtime. Such as OutOfMemory error. These JVM errors and you can not repair them at runtime. While exceptions are conditions that occur because of bad input etc. e.g. FileNotFoundException will be thrown if the specified file does not exist. Or a NullPointerException will take place if you try using a null reference. In most of the cases it is possible to recover from an exception (probably by giving user a feedback for entering proper values etc.).
How to create custom exceptions?
Your class should extend class Exception, or some more specific type thereof.
If I want an object of my class to be thrown as an exception object, what should I do?
The class should extend from Exception class. Or you can extend your class from some more precise exception type also.
If my class already extends from some other class what should I do if I want an instance of my class to be thrown as an exception object?
One can not do anything in this scenario. Because Java does not allow multiple inheritance and does not provide any exception interface as well.
How does an exception permeate through the code?
An unhandled exception moves up the method stack in search of a matching When an exception is thrown from a code which is wrapped in a try block followed by one or more catch blocks, a search is made for matching catch block. If a matching type is found then that block will be invoked. If a matching type is not found then the exception moves up the method stack and reaches the caller method. Same procedure is repeated if the caller method is included in a try catch block. This process continues until a catch block handling the appropriate type of exception is found. If it does not find such a block then finally the program terminates.
What are the different ways to handle exceptions?
There are two ways to handle exceptions,
1. By wrapping the desired code in a try block followed by a catch block to catch the exceptions. and
2. List the desired exceptions in the throws clause of the method and let the caller of the method handle those exceptions.
What is the basic difference between the 2 approaches to exception handling.
1. try catch block and
2. specifying the candidate exceptions in the throws clause?
When should you use which approach?
In the first approach as a programmer of the method, you yourself are dealing with the exception. This is fine if you are in a best position to decide should be done in case of an exception. Whereas if it is not the responsibility of the method to deal with it's own exceptions, then do not use this approach. In this case use the second approach. In the second approach we are forcing the caller of the method to catch the exceptions, that the method is likely to throw. This is often the approach library creators use. They list the exception in the throws clause and we must catch them. You will find the same approach throughout the java libraries we use.

Is it necessary that each try block must be followed by a catch block?
It is not necessary that each try block must be followed by a catch block. It should be followed by either a catch block OR a finally block. And whatever exceptions are likely to be thrown should be declared in the throws clause of the method.
If I write return at the end of the try block, will the finally block still execute?
Yes even if you write return as the last statement in the try block and no exception occurs, the finally block will execute. The finally block will execute and then the control return.
If I write System.exit (0); at the end of the try block, will the finally block still execute?
No in this case the finally block will not execute because when you say System.exit (0); the control immediately goes out of the program, and thus finally never executes.
How are Observer and Observable used?
Objects that subclass the Observable class maintain a list of observers. When an Observable object is updated it invokes the update() method of each of its observers to notify the observers that it has changed state. The Observer interface is implemented by objects that observe Observable objects.
What is synchronization and why is it important?
With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources. Without synchronization, it is possible for one thread to modify a shared object while another thread is in the process of using or updating that object's value. This often leads to significant errors.
How does Java handle integer overflows and underflows?
It uses those low order bytes of the result that can fit into the size of the type allowed by the operation.
Does garbage collection guarantee that a program will not run out of memory?
Garbage collection does not guarantee that a program will not run out of memory. It is possible for programs to use up memory resources faster than they are garbage collected. It is also possible for programs to create objects that are not subject to garbage collection .
What is the difference between preemptive scheduling and time slicing?
Under preemptive scheduling, the highest priority task executes until it enters the waiting or dead states or a higher priority task comes into existence. Under time slicing, a task executes for a predefined slice of time and then reenters the pool of ready tasks. The scheduler then determines which task should execute next, based on priority and other factors.
When a thread is created and started, what is its initial state?
A thread is in the ready state after it has been created and started.
What is the purpose of finalization?
The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup processing before the object is garbage collected.
What is the Locale class?
The Locale class is used to tailor program output to the conventions of a particular geographic, political, or cultural region.
What is the difference between a while statement and a do statement?
A while statement checks at the beginning of a loop to see whether the next loop iteration should occur. A do statement checks at the end of a loop to see whether the next iteration of a loop should occur. The do statement will always execute the body of a loop at least once.
What is the difference between static and non-static variables?
A static variable is associated with the class as a whole rather than with specific instances of a class. Non-static variables take on unique values with each object instance.
How are this() and super() used with constructors?
This() is used to invoke a constructor of the same class. super() is used to invoke a superclass constructor.
What are synchronized methods and synchronized statements?
Synchronized methods are methods that are used to control access to an object. A thread only executes a synchronized method after it has acquired the lock for the method's object or class. Synchronized statements are similar to synchronized methods. A synchronized statement can only be executed after a thread has acquired the lock for the object or class referenced in the synchronized statement.
What is daemon thread and which method is used to create the daemon thread?
Daemon thread is a low priority thread which runs intermittently in the back ground doing the garbage collection operation for the java runtime system. setDaemon method is used to create a daemon thread.

Can applets communicate with each other?
At this point in time applets may communicate with other applets running in the same virtual machine. If the applets are of the same class, they can communicate via shared static variables. If the applets are of different classes, then each will need a reference to the same class with static variables. In any case the basic idea is to pass the information back and forth through a static variable.

An applet can also get references to all other applets on the same page using the getApplets() method of java.applet.AppletContext. Once you get the reference to an applet, you can communicate with it by using its public members.

It is conceivable to have applets in different virtual machines that talk to a server somewhere on the Internet and store any data that needs to be serialized there. Then, when another applet needs this data, it could connect to this same server. Implementing this is non-trivial.
What are the steps in the JDBC connection?
While making a JDBC connection we go through the following steps :
Step 1 : Register the database driver by using :
Class.forName(\" driver classs for that specific database\" );
Step 2 : Now create a database connection using :
Connection con = DriverManager.getConnection(url,username,password);
Step 3: Now Create a query using :
Statement stmt = Connection.Statement(\"select * from TABLE NAME\");
Step 4 : Exceute the query :
stmt.exceuteUpdate();
How does a try statement determine which catch clause should be used to handle an exception?
When an exception is thrown within the body of a try statement, the catch clauses of the try statement are examined in the order in which they appear. The first catch clause that is capable of handling the exceptionis executed. The remaining catch clauses are ignored.
Can an unreachable object become reachable again?
An unreachable object may become reachable again. This can happen when the object's finalize() method is invoked and the object performs an operation which causes it to become accessible to reachable objects.
What method must be implemented by all threads?
All tasks must implement the run() method, whether they are a subclass of Thread or implement the Runnable interface.
What are synchronized methods and synchronized statements?
Synchronized methods are methods that are used to control access to an object. A thread only executes a synchronized method after it has acquired the lock for the method's object or class. Synchronized statements are similar to synchronized methods. A synchronized statement can only be executed after a thread has acquired the lock for the object or class referenced in the synchronized statement.
What is Externalizable?
Externalizable is an Interface that extends Serializable Interface. And sends data into Streams in Compressed Format. It has two methods, writeExternal(ObjectOuput out) and readExternal(ObjectInput in)
What modifiers are allowed for methods in an Interface?
Only public and abstract modifiers are allowed for methods in interfaces.
What are some alternatives to inheritance?
Delegation is an alternative to inheritance. Delegation means that you include an instance of another class as an instance variable, and forward messages to the instance. It is often safer than inheritance because it forces you to think about each message you forward, because the instance is of a known class, rather than a new class, and because it doesn't force you to accept all the methods of the super class: you can provide only the methods that really make sense. On the other hand, it makes you write more code, and it is harder to re-use (because it is not a subclass).
What does it mean that a method or field is "static"?
Static variables and methods are instantiated only once per class. In other words they are class variables, not instance variables. If you change the value of a static variable in a particular object, the value of that variable changes for all instances of that class.
Static methods can be referenced with the name of the class rather than the name of a particular object of the class (though that works too). That's how library methods like System.out.println() work out is a static field in the java.lang.System class.
What is the difference between preemptive scheduling and time slicing?
Under preemptive scheduling, the highest priority task executes until it enters the waiting or dead states or a higher priority task comes into existence. Under time slicing, a task executes for a predefined slice of time and then reenters the pool of ready tasks. The scheduler then determines which task should execute next, based on priority and other factors.
What is the catch or declare rule for method declarations?
If a checked exception may be thrown within the body of a method, the method must either catch the exception or declare it in its throws clause.

Is Empty .java file a valid source file?
Yes, an empty .java file is a perfectly valid source file.
Can a .java file contain more than one java classes?
Yes, a .java file contain more than one java classes, provided at the most one of them is a public class.
Is String a primitive data type in Java?
No String is not a primitive data type in Java, even though it is one of the most extensively used object. Strings in Java are instances of String class defined in java.lang package.
Is main a keyword in Java?
No, main is not a keyword in Java.
Is next a keyword in Java?
No, next is not a keyword.
Is delete a keyword in Java?
No, delete is not a keyword in Java. Java does not make use of explicit destructors the way C++ does.
Is exit a keyword in Java?
No. To exit a program explicitly you use exit method in System object.
What happens if you don't initialize an instance variable of any of the primitive types in Java?
Java by default initializes it to the default value for that primitive type. Thus an int will be initialized to 0, a Boolean will be initialized to false.
What will be the initial value of an object reference which is defined as an instance variable?
The object references are all initialized to null in Java. However in order to do anything useful with these references, you must set them to a valid object, else you will get NullPointerException everywhere you try to use such default initialized references.
What are the different scopes for Java variables?
The scope of a Java variable is determined by the context in which the variable is declared. Thus a java variable can have one of the three scopes at any given point in time.
1. Instance : - These are typical object level variables, they are initialized to default values at the time of creation of object, and remain accessible as long as the object accessible.
2. Local : - These are the variables that are defined within a method. They remain accessible only during the course of method execution. When the method finishes execution, these variables fall out of scope.
3. Static: - These are the class level variables. They are initialized when the class is loaded in JVM for the first time and remain there as long as the class remains loaded. They are not tied to any particular object instance.
What is the default value of the local variables?
The local variables are not initialized to any default value, neither primitives nor object references. If you try to use these variables without initializing them explicitly, the java compiler will not compile the code. It will complain about the local variable not being initialized..
How many objects are created in the following piece of code? MyClass c1, c2, c3;
c1 = new MyClass ();
c3 = new MyClass ();
Only 2 objects are created, c1 and c3. The reference c2 is only declared and not initialized.
Can a public class MyClass be defined in a source file named YourClass.java?
No the source file name, if it contains a public class, must be the same as the public class name itself with a .java extension.
Can main method be declared final?
Yes, the main method can be declared final, in addition to being public static.
What will be the output of the following statement?
System.out.println ("1" + 3);
It will print 13.
What will be the default values of all the elements of an array defined as an instance variable?
If the array is an array of primitive types, then all the elements of the array will be initialized to the default value corresponding to that primitive type. e.g. All the elements of an array of int will be initialized to 0, while that of Boolean type will be initialized to false. Whereas if the array is an array of references (of any type), all the elements will be initialized to null.

Top 10 browser Extension For WEB Developers

noreply@blogger.com (Anonymous) — Mon, 15 Aug 2011 08:01:00 +0000

Firefox: Page Speed

Page Speed is an open-source Firefox/Firebug Add-on. Web masters and web developers can use Page Speed to evaluate the performance of their web pages and to get suggestions on how to improve them. I use Page Speed to optimize my websites.

Chrome: Speed Tracer

Speed Tracer is a tool to help you identify and fix performance problems in your web applications. It visualizes metrics that are taken from low level instrumentation points inside of the browser and analyzes them as your application runs. Speed Tracer is available as a Chrome extension and works on all platforms where extensions are currently supported (Windows and Linux).

Firefox: FireBug

Firebug integrates with Firefox allowing you to edit, debug, and monitor CSS, HTML, and JavaScript live in any web page.

Chrome: Firebug Lite

Firebug team also creates extension for Chrome. So far I have not been able to use firebug in chrome. I am running Google Chrome 5.0.307.11 Beta under Ubuntu Karmic 9.10

Firefox: HTML Validator

HTML Validator is a Mozilla extension that adds HTML validation inside Firefox and Mozilla. The number of errors of a HTML page is seen on the form of an icon in the status bar when browsing.

Chrome: Validity

Validity can be used to quickly validate your HTML documents from the address bar. We can either click the icon in the address bar or press Ctrl + Alt + V to validate the HTML document. My experience with validity is that sometimes the icon does not appear in your address bar, so I need to press the short cut key to activate it. It display the number of HTML validation errors, but yet it does not list out what the errors are or how to fix it unlike firefox HTML validator. Validity allow you to install our own HTML validator such as the W3C HTML Validation

Firefox:Colorzilla

With ColorZilla you can get a color reading from any point in your browser, quickly adjust this color and paste it into another program. You can Zoom the page you are viewing and measure distances between any two points on the page. The built-in palette browser allows choosing colors from pre-defined color sets and saving the most used colors in custom palettes. DOM spying features allow getting various information about DOM elements quickly and easily.

Chrome: Eye Dropper

Eye Dropper is chrome’s equal to colorzilla.

Firefox: Firesizer

Firesizer allow developer to resize their firefox browser into specific dimension.

Chrome: Resolution Test

Resolution Test changes the size of the browser window for developers to preview their websites in different screen
resolutions. It includes a list of commonly used resolutions as well as a custom option for you to input your own

Resources:

1. Page Speed
2. Speed Tracer
3. FireBug
4. Firebug Lite
5. HTML Validator
6.Validity
7. Colorzilla
8. Eye Dropper
9. Firesizer
10. Resolution Test

Top 50 Sites For CSS3 Example and Downloads

noreply@blogger.com (Anonymous) — Sat, 13 Aug 2011 12:44:00 +0000

1- CSS3 Dropdown Menu

2- Pure CSS3 Download Button

3- CSS3 Gets a New Logo

4- Advanced CSS3 Menu

5- Amazing CSS3 Template

6- css3 web design examples

7- CSS3 jQuery Album Selection

8- CSS3 Minimalistic Navigation Menu

9- Accordian Effect Using CSS

10- Use CSS3 to Create a Dynamic Stack of Index Cards

11- CSS3 Generator

12- Subtle Rounded Corners and Shadow

13- Pictos font and CSS3

14- Creating a Fun Animated Navigation Menu With Pure CSS

15- Sweet CSS3 Buttons

16- Animated Navigation Menu with CSS3

Windows7 Start Menu CSS3

18- Rounded Corners

19- Rotating Images With CSS3

20- CSS3 tyle Sliders

21- My Notes With Html5 CSS3 jQuery

22- Create a CSS3 Menu Using moz border radius

23- CSS3 popup links

24- Contextual Slideout Tips CSS3

25- A Fresh Bottom Slide Out Menu with jQuery CSS3

26- CSS3 Drop Down Menu With Integrated Forms

27- Animation Using CSS Transforms

28- Trippy Spinning Column of Fun CSS3

29- CSS3 Lightbox Gallery With jQuery

30- Easily Turn Your Images Into Polaroids with CSS3

31- Leaves CSS3

32- Star Wars Crawl CSS3

33- Rotating One Large Image CSS3

34- Rotating Multiple Large Images CSS3

35- Alternatives CSS3

37- CSS3 jQuery Tickets Machine

38- Awesome Cufonized CSS3

39- Relying on CSS3

40- Map Pins CSS3

41- Export Rotated Image Instead CSS3

42- CSS3 Thumbs

43- How to Build a Kick Butt CSS3

44- CSS3 Button Maker

45- CSS3 Menu Creator

46- Fading Transition

47- CSS3 Style Maker

48- Sweet Tabbed Navigation Using CSS3

49- CSS3 Multi Column Generator

50- Create a Slick Menu Using CSS3

51- The Cross Browser CSS3 Rule Generator

FaceBook - Revert backs the old chat style

noreply@blogger.com (Anonymous) — Mon, 25 Jul 2011 13:08:00 +0000

install to get back old fb chat

VasanSoft Chat Mechanic for Greasemonkey

Revert backs the old chat style.

go to link and then click on Install

Dumps

noreply@blogger.com (Anonymous) — Mon, 25 Jul 2011 12:21:00 +0000

Tivoli Directory Server Certification Exam Dumps

http://www.easy-share.com/1916900197/000-928 (1).zip
http://www.easy-share.com/1916900169/000-928.zip

All the Best

Top 13 ways to know : how to search in Google

noreply@blogger.com (Anonymous) — Wed, 25 May 2011 18:38:00 +0000

Google is clearly the best general-purpose search engine on the Web and Google goes far beyond a regular search engine. Give the tricks in this article a try. You’ll be amazed at how many different ways Google can improve your Internet searching. In addition to the basic AND, OR, and phrase searches, Google offers some rather extensive special syntax for narrowing your searches.
But most people don’t use google to its best advantage. Do you just plug in a keyword or two and hope for the best? That may be the quickest way to search, but with more than ten billion pages inGoogle’s index, it’s still a struggle to compare results to a manageable number. Google is an remarkably powerful tool that can ease and enhance your Internet exploration. Google’s search options go beyond simple keywords, the Web, and even its own programmers. Let’s look at some of Google’s lesser-known options.
Using special syntax you can tell Google that you want to restrict your searches to certain elements or characteristics of Web pages. Google has listed a complete list of its syntax elements at www.google.com/help/operators.html
So lets Discuss these special syntax elements:

Calculator:
The next time you need to do a quick calculation, instead of bringing up the Calculator applet, you can just type your expression in toGoogle.
Example:
48512 * 1.02
Word Definitions:
If you need to quickly look up the definition of a word or phrase, simply use the “define:” command.
Example:
define:internet
intitle:
This Syntax restricts your search to the titles of web pages. The variation allintitle: finds pages wherein all the words specified appear in the title of the web page. Using allintitle: is basically the same as using the intitle: before each keyword.
examples:
intitle:”george bush”
allintitle:”money supply” economics
You may wish to avoid the allintitle: variation, because it doesn’t mix well with some of the other syntax elements.
intext:
This Syntax searches only body text (i.e., ignores link text, URLs, and titles). While its uses are limited, it’s perfect for finding query words that might be too common in URLs or link titles.
examples:
Intext:”hacker9.com”
Intext:html
There’s also an allintext: variation, but again, this doesn’t play well with others.
inanchor:
This Syntax searches for text in a page’s link anchors. A link anchor is the descriptive text of a link. For example, the link anchor in the HTML code
example:
inanchor:”hacker9″
As with other in*: syntax elements, there’s an allinanchor: variation, which works in a similar way (i.e., all the keywords specified must appear in a page’s link anchors).
Link:
Lets you see which pages are linking to your Web page or to another page you’re interested in.
example:
link:http://www.hacker9.com
site:
This Syntax allows you to narrow your search by either a site or a top-level domain.
examples:
site:hacker9.com hacks
site:edu
site:nc.us
inurl:
restricts your search to the URLs of web pages. This syntax tends to work well for finding search and help pages, because they tend to be rather regular in composition.
example:
inurl:help
You’ll see that using the inurl: query instead of the site: query has one immediate advantage you can use it to search subdirectories. While the http:// prefix in a URL is ignored byGoogle when used with site:, search results come up short when including it in an inurl: query. Be sure to remove prefixes in any inurl: query for the best (read: any) results.
You can also use inurl: in combination with the site: syntax to draw out information on subdomains. For example, how many subdomains does google.com really have? A quick query will help you figure that out:
example:
site:google.com -inurl:www.google.com
This query asks Google to list all pages from the google.com domain, but leave out those pages which are from the common subdomain www, since you already know about that one
Do you ever wonder how many subdomains google has.I wondered!!!!
cache:
cache: finds a copy of the page that Google indexed even if that page is no longer available at its original URL or has since changed its content completely.
example:
cache:hacker9.com
If Google returns a result that appears to have little to do with your query, you’re almost sure to find what you’re looking for in the latest cached version of the page atGoogle. The Google cache is particularly useful for retrieving a previous version of a page that changes often.
filetype:
filetype: searches the suffixes or filename extensions. These are usually, but not necessarily, different file types; filetype:htm and filetype:html will give you different result counts, even though they’re the same file type. You can even search for different page generators—such as ASP, PHP, CGI, and so forth—presuming the site isn’t hiding them behind redirection and proxying.Google indexes several different Microsoft formats, including PowerPoint (.ppt), Excel (.xls), and Word (.doc).
examples:
“learn java” filetype:pdf
“IT books” filetype:doc
related:
related:, as you might expect, finds pages that are related to the specified page. This is a good way to find categories of pages; a search for related:google.com returns a variety of search engines, including Lycos, Yahoo!, and Northern Light.
examples:
related:www.yahoo.com
related:www.cnn.com
While an increasingly rare occurrence, you’ll find that not all pages are related to other pages.
info:
info: provides a page of links to more information about a specified URL. This information includes a link to the URL’s cache, a list of pages that link to the URL, pages that are related to the URL, and pages that contain the URL.
examples:
info:www.hacker9.com
info:www.nytimes.com/technology
Note that this information is dependent on whether Google has indexed the specified URL; if not information will obviously be far more limited.
phonebook:
This Syntex as you might expect, looks up phone numbers.
examples:
phonebook:ashwin IN
phonebook:(511) 556-2725
Source: Google features

Free Downloading Tricks with Google

noreply@blogger.com (Anonymous) — Wed, 25 May 2011 18:31:00 +0000

With regular way of searching on Google, we do miss lots of things that we are searching for. There are lot of pro ways to search Internet Using Google and are more effective and very informative than normal way. In this post i will show you how to achieve your needs with Google using simple search queries. This trick works fairly decent for finding mp3′s on the web, which is hard to do normally. You can use the same trick to find other files too for example: avi, mp3, mpg, torrents, etc.

Finding Music files using Google.

Lets say you want to download a “Coldplay-Life In Technicolor” song. Just type in the below Search Query in the search bar -

“index of/” “Coldplay-Life In Technicolor” .mp3

note: you can replace ‘Coldplay-Life In Technicolor‘ with file Name of your choice and .mp3 with other extension.
In the Search Results you got to check out the results that starts with “Index of/” in the title. This technique allows you to easily pull up web folders with direct download links. it will look the same as if you were logged into a ftp URL. I’m sure you can be pretty flexible on how you type that in, as long as you include “index of/”. it’s not perfect but it has worked for me on a few occasions.

Finding Other Files

Now that you already know how to find mp3 file, finding other files is quite the same. see the below query.

filename filetype:type

Ex: lets say you want to search Microsoft XP Installer package (torrent file), Then you you will type the below query:
Microsoft xp Installer filetype:torrent
Finding Movies

“parent directory ” DVDRip -xxx -html -htm -php -shtml -opendivx -md5 -md5sums

“parent directory “Xvid -xxx -html -htm -php -shtml -opendivx -md5 -md5sums

Finding Applications

“parent directory ” /appz/ -xxx -html -htm -php -shtml -opendivx -md5 -md5sums

Finding Flash games

“parent directory ” Gamez -xxx -html -htm -php -shtml -opendivx -md5 -md5sums

The above strings are all same. I just changed their second part to find various things. You can make changes in parts of this string and do experiments for more better results.

Top Youtube Search Commands You May Not Know About

noreply@blogger.com (Anonymous) — Wed, 25 May 2011 18:28:00 +0000

Today we will See how you can get Accurate Video search results on Youtube using simple Commands in plain English. Now a days Webmasters are also optimizing their videos using simple SEO techniques and that’s the reason you might end up getting Wrong search results, just like Google.
Am sure these commands will certainly help improve your productivity on Youtube and make your day today video search Simple. So here’s are the 8 lesser known Youtube search commands:

#1. channel – This Searches only YouTube channels
#2. this week | today | this month - Searches videos uploaded in the given time frame.
#3. partner – Searches for video uploaded by YouTube partners only.
#4. movie – Searches for full length movies available on YouTube.
#5. hd - Limits only HD quality videos.
#6. 3d – Limits only 3D videos.
#7. playlist – returns only videos in playlists.
#8. long – Returns videos that are 20 minutes or longer
To use the Above simple search commands all you have to do is type in your search followed by a comma and the command. Example:

Eminem, this month
Microsoft, 3d

#9. You can also mix or combine the above commands with commas and apply them all to your search query.

Example: Eminem, this month, hd

The above Query will return all the HD videos of Eminem that have been uploaded to YouTube this month.

resource: hacker9

Pirates Of The Caribbean 4 - On Stranger Tides

noreply@blogger.com (Anonymous) — Fri, 20 May 2011 14:32:00 +0000

BackTrack Linux

noreply@blogger.com (Anonymous) — Fri, 20 May 2011 05:54:00 +0000

BackTrack is a Linux-based penetration testing arsenal that aids security professionals in the ability to perform assessments in a purely native environment dedicated to hacking. Regardless if you’re makingBackTrack you Install BackTrack, boot it from a Live DVD or thumbdrive, the penetration distribution has been customized down to every package, kernel configuration, script and patch solely for the purpose of the penetration tester.

BackTrack 5 - Penetration Testing Distribution from Offensive Security on Vimeo.

Tools

BackTrack provides users with easy access to a comprehensive and large collection of security-related tools ranging from port scanners to password crackers. Support for Live CD and Live USB functionality allows users to boot BackTrack directly from portable media without requiring installation, though permanent installation to hard disk is also an option.
BackTrack includes many well known security tools including:

Metasploit integration
RFMON Injection capable wireless drivers
Kismet
Nmap
Ophcrack
Ettercap
Wireshark (formerly known as Ethereal)
BeEF (Browser Exploitation Framework)
Hydra
Cisco OCS Mass Scanner A very reliable and fast scanner for Cisco routers with telnet/enable default password.
Quypt (Terminal Emulator) (which is private software by Crimson Hacking group, which has leaked to the Mainstream) Blackhat
A large collection of exploits as well as more commonplace software such as browsers.

BackTrack arranges tools into 11 categories:

Information Gathering
Network Mapping
Vulnerability Identification
Web Application Analysis
Radio Network Analysis (802.11, Bluetooth, RFID)
Penetration (Exploit & Social Engineering Toolkit)
Privilege Escalation
Maintaining Access
Digital Forensics
Reverse Engineering
Voice Over IP

version Released

Date	Release
February 5, 2006	BackTrack v.1.0 Beta
May 26, 2006	The BackTrack project released its first non-beta version (1.0).
March 6, 2007	BackTrack 2 final released.
June 19, 2008	BackTrack 3 final released.
January 9, 2010	BackTrack 4 final release. (Now based on Debian)
May 8, 2010	BackTrack 4 R1 release
November 22, 2010	BackTrack 4 R2 release
May 10, 2011	BackTrack 5 release (Based on Ubuntu 10.04 LTS, Linux kernel 2.6.38)

Download BackTrack

live operating system

noreply@blogger.com (Anonymous) — Fri, 20 May 2011 05:37:00 +0000

Without Free Live Operating System CD’s and DVD’s many of us wouldn’t be able to troubleshoot PC? MAC or Laptop problems now days or simply copy and paste the files from one hard drive to another. You operating system is hosed and you can’t boot , what you are going to do? Hit F8? NO! Boot the Live CD, and troubleshoot with these Five Best Live CD’s voted by LifeHacker’s poll.

* Knopix – Linux operating system with many extra tools to fix your operating system problem.
* Ultimate Boot CD for Windows – Windows based Operating system, great live cd for windows users
* Puppy Linux – Another best friend yet for? Linux Breed.
* Back Track – Has some advanced unix/linux stuff, would recommend for experts.
* Ubuntu – My favorite and very easy to use Live CD

A live CD, live DVD, or live disc is a CD or DVD containing a bootable computer operating system. Live CDs are unique in that they have the ability to run a complete, modern operating system on a computer lacking mutable secondary storage, such as a hard disk drive. Live USB flash drives are similar to live CDs, but often have the added functionality of automatically and transparently writing changes back to theirbootable medium.

The term "live" derives from the fact that these CDs each contain a complete, functioning and operational operating system on the distribution medium.

While a live CD typically does not alter any operating system or files already installed on a computer's secondary storage (such ashard disk drives), many live CDs include mechanisms and utilities for altering the host computer's data stores, including installation of an operating system. This is important for the system management aspect of live CDs, such as removing malware, drive imaging, and system recovery.

The default option, however, is to allow the user to return the computer to its previous state when the live CD is ejected and the computer is rebooted. It is able to run without permanent installation by placing the files that typically would be stored on a hard drive into RAM, typically in a RAM disk, though this does cut down on the RAM available to applications.

Some live CDs come with an installation utility launchable from a desktop icon that can optionally install the system on a hard drive or USB flash drive. Most live CDs can access the information on internal and/or external hard drives, diskettes and USB flash drives.

Generally live CDs are booted from read-only media, requiring either copying to rewriteable media (i.e. a hard drive) or complete remastering to install additional software; however, there are exceptions such as Puppy Linux which has the ability to save files to the live CD itself or other multisession media, allowing users to carry data, and more importantly, added programs and customized settings, along with them on optical disc.

Most live CDs are based on Linux, as this was the operating system that had the most to gain by offering free trials and demonstrations without regard to sales or copyright. Now others are using the term live CD for other operating systems, such as OpenSolaris, BeleniX and others based on Solaris. Other "live" operating systems include Mac OS, Microsoft Windows, OS/2, ReactOS, NetBSD, FreeBSD, OpenBSD, MINIX 3, Plan 9 from Bell Labs, AmigaOS 4, MorphOS and FreeDOS.

The first personal computer operating system on a CD to support "live" operations might have been the AmigaOS, which could be booted from CD on an Amiga CDTV in 1990.[citation needed]. Earlier examples of live OS are of course the operating systems used from floppy, and most widely spread is DOS.

Unlike previous operating systems on optical media, though, Linux and OS/2 "live CDs" were specifically designed to run without installation onto other media like a hard disk drive. The live CD concept was meant to promote Linux and showcase the abilities of the free, open source operating system on conventional personal computers with Microsoft Windows already installed.[citation needed]

On a PC, a bootable Compact Disc generally conforms to the El Torito specification. Many Linux based live CDs use a compressed filesystem image, often with the cloop compressed loopback driver, or squashfs compressed filesystem, generally doubling effective storage capacity, although slowing application start up[citation needed].

The resulting environment can be quite rich: typical Knoppix systems include around 1,200 separate software packages. Live CDs have a reputation for supporting advanced auto-configuration and plug-and-play functionality. This came out of necessity to avoid requiring the user to configure the system each time it boots and to make it easily usable by those who are new to the operating system.
Technique

A read-only file system, such as on a CD-ROM has the drawback of being unable to save any current working data. For this reason, a read-only file system is often merged with a temporary writable file system in the form of a RAM disk. Often the default Linux directories "/home" (containing users' personal files and configuration files) and "/var" (containing variable data) are kept in ramdisk, because the system updates them frequently. Puppy linux has a savable layer so if you choose to, the next time you boot you can resume (pick right back up again) from where you left off. Each time the CD boots, it looks for the file and then uses it if it has the right name.

In modern live CDs, a read-only file system is merged with ramdisk using transparent techniques such as UnionFS, AuFS or EWF. In MS-DOS and OS/2 systems, ramdrive.sys, can be loaded at boot for this purpose. Boot loaders like syslinux can boot ISO files from USB memory devices.

Live CDs have to be able to detect and use a wide variety of hardware (including network cards, graphic cards etc.) in realtime. This is easily achieved nowadays by udev, hotplug, hal, udisk etc.. which is a common part of all distributions based on Linux kernel 2.6.

Boot code
During live CD initialization, a user typically may resort to using one or more boot codes to change the booting behavior. These vary from distribution to distribution but can most often be accessed upon firstboot screen by one of the function keys.

Architecture of the Servlet Package

noreply@blogger.com (Anonymous) — Mon, 16 May 2011 09:24:00 +0000

The javax.servlet package provides a set of interfaces and classes for writing servlets.

These classes and interfaces are normally found in 'Enterprise Edition' versions of the Java SDK. They are also included within TJI's ide.jar so that servlets can be developed by those without an EE SDK.

The architecture of the servlet package is described below.

The Servlet Interface

The central abstraction in the Servlet API is the Servlet interface. The Servlet interface declares, but does not implement, methods that manage the servlet and its communications with clients. All servlets implement this interface, either directly or, more commonly, by extending a class that does implement it, such asGenericServlet or HttpServlet.

For class GenericServlet, or a class extending it, the main method involved in client interaction is the service(ServletRequest, ServletResponse) method. For class HttpServlet, the default Http request type is 'GET' and the main method called to handle this is the method doGet(HttpServletRequest, HttpServletResponse).

An Example Servlet

A servlet can be as simple as this :

public class HelloWorldServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) {
response.getWriter().println("Hello World !");
}
}

Client Interaction

When a servlet receives a call from a client, it receives two objects (provided by the Java web server):

A ServletRequest, which encapsulates the communication from the client to the server, and
A ServletResponse, which encapsulates the communication from the servlet back to the client.

ServletRequest and ServletResponse are interfaces defined by the javax.servlet package.

The ServletRequest Interface

The ServletRequest interface allows the servlet access to:

Information, such as the names of the parameters passed from the client, the protocol (scheme) being used by the client, and the names of the remote host that made the request and the server that received it.
The input stream, ServletInputStream. Servlets can use this input stream to get data from the client when using an application protocol such as the http POST method.

Interfaces that extend the ServletRequest interface allow the servlet to retrieve more protocol-specific data. For example, the HttpServletRequest interface contains methods for accessing HTTP-specific header information, such as any cookies found in the request and the HTTP method type with which the request was made.

The ServletResponse Interface

The ServletResponse interface defines the servlet methods for replying to a client. It:

Allows the servlet to set the content length and MIME type of the reply.
Provides an output stream, ServletOutputStream, and a Writer through which the servlet can send the reply data. Using the writer is the simplest choice when the reply data is of MIME type 'text/html'.

Interfaces that extend the ServletResponse interface give the servlet more protocol-specific capabilities. For example, the HttpServletResponse interface contains methods that allow the servlet to set HTTP-specific header information.

The Additional Capabilities of HTTP Servlets

The classes and interfaces described above make up a basic Servlet. HTTP servlets have some additional objects that provide Session-tracking capabilities. The servlet writer can use these APIs to maintain state between the servlet and the client that persists across multiple connections during some time period. HTTP servlets also have objects that provide cookies. The servlet writer can use the Cookie API to save data with the client and to retrieve this data. See the 'Sessions Tracking' and 'Using Cookies' sections for more information on these topics.

Connecting ASP with DataBase with Example

noreply@blogger.com (Anonymous) — Mon, 16 May 2011 06:39:00 +0000

Before a database can be accessed from a web page, a database connection has to be established.

Create a DSN-less Database Connection

The easiest way to connect to a database is to use a DSN-less connection. A DSN-less connection can be used against any Microsoft Access database on your web site.

If you have a database called "northwind.mdb" located in a web directory like "c:/webdata/", you can connect to the database with the following ASP code:

<%

set conn=Server.CreateObject("ADODB.Connection")

conn.Provider="Microsoft.Jet.OLEDB.4.0"

conn.Open "c:/webdata/northwind.mdb"

%>

Note, from the example above, that you have to specify the Microsoft Access database driver (Provider) and the physical path to the database on your computer.

Create an ODBC Database Connection

If you have an ODBC database called "northwind" you can connect to the database with the following ASP code:

<%

set conn=Server.CreateObject("ADODB.Connection")

conn.Open "northwind"

%>

With an ODBC connection, you can connect to any database, on any computer in your network, as long as an ODBC connection is available.

Form to database Tutorial in ASP

Download the code

We are going to create 2 pages. The first will display a simple HTML form and the second will be an ASP page (known as the action page) which will process the data sent by the form and insert it into our Access database. We will be using a DSN-less connection.

Create a page and name it 'form.html'. Copy the following code into it.

<html>
<head>
<title>Form to Database</title>
</head>
<body>

<form name="form1" action="add_to_database.asp" method="post">
<div align="center">
<table width="80%" border="0">
<tr>
<td>Name :</td>
<td><input type="text" name="name"></td>
</tr>
<tr>
<td>Email :</td>
<td> <input type="text" name="email"></td>
</tr>
<tr>
<td>Comments :</td>
<td><textarea name="comments"></textarea></td>
</tr>
<tr>
<td> </td>
<td><input type="submit" value="submit details" name="submit"></td>
</tr>
</table>
</div>
</form>

</body>
</html>

The above code creates a simple form asking for name, email and comments.
The form knows which page to post the details too i.e. action="add_to_database.asp"

Now onto the ASP action page, i.e. the page that will receive the details sent from the form and process them.

Create a new ASP page called 'add_to_database.asp'. Keep it in the same folder as 'form.html'. Copy and paste the following ASP code into 'add_to_database.asp'.

<%@ Language="VBScript" %>
<% Option Explicit %>
<html>
<head>
<title>Form to database</title>
</head>
<body>
<%
'declare your variables
Dim name, email, comments
Dim sConnString, connection, sSQL
'Receiving values from Form, assign the values entered to variables
name = Request.Form("name")
email = Request.Form("email")
comments =Request.Form("comments")

'declare SQL statement that will query the database
sSQL = "INSERT into users_tbl (name, email, comments) values ('" & _
name & "', '" & email & "', '" & comments & "')"
'define the connection string, specify database
'driver and the location of database
sConnString="PROVIDER=Microsoft.Jet.OLEDB.4.0;" & _
"Data Source=" & Server.MapPath("Users.mdb")
'create an ADO connection object
Set connection = Server.CreateObject("ADODB.Connection")

'Open the connection to the database
connection.Open(sConnString)

'execute the SQL
connection.execute(sSQL)

response.write "The form information was inserted successfully."
'Done. Close the connection object
connection.Close
Set connection = Nothing
%>
</body>
</html

Call our file 'show_records.asp'.

<%@ Language="VBScript" %>
<% Option Explicit %>
<html>
<head>
<title>Form to database - showing records</title>
</head>
<body>
<%
'declare your variables
Dim connection, recordset
Dim sSQL, sConnString

'declare SQL statement that will query the database
sSQL="SELECT * FROM Users_tbl"

'create an ADO connection and recordset object
Set connection = Server.CreateObject("ADODB.connection")
Set recordset = Server.CreateObject("ADODB.Recordset")

'define the connection string, specify database
'driver and the location of database
sConnString="PROVIDER=Microsoft.Jet.OLEDB.4.0;" & _
"Data Source=" & Server.MapPath("Users.mdb")

'Open the connection to the database
Connection.Open sConnString

'Open the recordset object, executing the SQL
Recordset.Open sSQL, Connection

'Looping through the records until the end of the records
Do while Not recordset.eof
Response.Write "Name : " & recordset("name") & "<br>"
Response.Write "Email : " & recordset("email") & "<br>"
Response.Write "Comments : " & recordset("comments") & "<br><br>"
'move on to the next record
recordset.MoveNext
loop

'Now close the recordset and the connection object
recordset.Close
Set recordset = Nothing
connection.Close
Set connection = Nothing
%>
</body>
</html>

Tomcat Architecture (4.x) Detailed

noreply@blogger.com (Anonymous) — Sun, 15 May 2011 15:18:00 +0000

Tomcat is a feature complete servlet container that Java servlets and JSP can be run. In many cases tomcat is used with Apache server to serve dynamic content to a web page.

J2EE
Java 2 Platform Enterprise Edition (J2EE) defines a group of Java-based code libraries (called API in the Java world) that are suited to creating web applications for the enterprise (i.e a large company).J2EE is design to cope with large complex configuration in large companies. J2EE is used in a distributed system environment where specific servers do specific tasks. There are many J2EE API's and here is a list of some key ones:

Enterprise JavaBeans (EJB)	EJB technology provides a simple mechanism for creating distributed business logic components.
Java Message Service (JMS)	Provides asynchronous messaging capability to J2EE applications
Java Naming and Directory Service (JDNI)	Enables J2EE applications to communicate with registries and directories services i.e LDAP
Servlets	Servlets work with special servers called servlet containers to process HTTP requests and send HTTP responses
JavaServer Pages (JSP)	JSP is an alternative, HTML-like interface for creating servlets. At runtime, the servlet container converts a JSP into a servlet

Tomcat
Tomcat is a servlet container and as a servlet container it is only required to implement the servlet and JSP API's and thus not consider a J2EE application server. The reason to use Tomcat is that it is a cut down version of the full J2EE environment as the other API's are not required.
JSP and Servlets
Servlets are portions of logic written in Java that have a defined form and which are invoked to dynamically generate content. A servlet has a defined lifecycle and were created by Sun microsystems due to the problems with CGI.
JSP is a technology to provide dynamic content, the programmer will insert code that can personalise and secure a web page, the Java code will be executed on the server rather than the browser. JSP pages are compiled intoservlets which are then kept in memory or on the filesystem indefinitely, until either the memory is required back or the server is restarted. This method increases response times as the document as already be parsed and compiled, the result works like a CGI program. The difference between JSP and sevlets is that sevlets are held within the private area of the server, while JSP are held within the public area. Jasper and Javac are the compilers that convert JSP pages into servlets.
JSP are often used like templates where many JSP pages make up a web page - see below fig.

JSP tag extensions encapsulate entire functions which makes the code more readable. Each tag has a corresponding Java class that contains the code that would otherwise appear on the page.
Web application architecture
The set of all the servlets, JSP pages and other files that are logically related composes a web application. The servlet specification defines a standard directory hierarcy where all of these files must be placed.

/	All pubicly files are placed in this directory i.e HTML, JSP and GIF
/WEB-INF	Files in this directory are private. A single file, web.xml called the deployment descriptor contains configuration options for the web application.
/WEB-INF/classes	web application classes are placed here
/WEB-INF/lib	Class files can be archived into a single file, called a JAR file and placed into this directory.

Tomcat installation
Follow the link for the installation guide
Tomcat Architecture
The server is tomcat itself, an instance of the web application server. It is possible to run two tomcat servers on the same machine using two different port numbers.
A service groups a container (usually of type engine) with that container's connectors and is the top-level component.
Connectors connect the applications to client. Ther are a number of connectors, HTTP, SSL, JDBC, WARP, etc
Engine is a request-processing component that represents the Catalina servlet engine. By examining the HTTP header it knows what engine to pass the request to.
Realms will reside inside the engine and manage authenication and authorisation. It applies across the entire engine within the container. So each engine will have its own realm.
Valves are components that intercept requests and pre-process it. Valves are commonly used to enable single sign-on for all hosts as well as log request patterns, client IP addresses and server usage patterns.
Listeners listen for significant events in the component they are configured in, for an example , a Javabean could send an email when an event requiring administration is recorded. In other words when a particular event occurs a certain action can be taken.
Loggers report on the internal state of a component. The default logger can be overridden thus given you seperate log files.
Hosts minics the popular Apache virtual host functionality.
Context is the web application itself.
Using the above information and the diagram below you should have a understanding of the tomcat architecture.
Fig 1

Main files that make up the tomcat server

server.xml	This is the main config file and is read at startup.
server-noexamples.xml	This file contains a blank template of the server.xml, it is ideal to use for your own main config file
tomcat-users.xml	This file contains user authenication and role mapping info for setting up a memory realm
web.xml	This file is the default deployment discriptor file for any web application that are running on the tomcat server instance.
catalina.policy	java 2 has a fine grain security model that enable the administrator to control in detail the accessibility of system resources.

How server.xml and web.xml work together
The URL below is parsed by the various components of tomcat.
https://www.datadisk.co.uk/bookstore/buybook/proApache
1. https:// - in this case the SSL connector is used and the request passed to the engine. (processed by server.xml)

2. www.datadisk.co.uk - is parsed by the engine and one of its hosts is selected. (processed by server.xml)

3. /bookstore - is matched agaist the entire context that it contains and the bookstore web application is selected. (processed by server.xml)

4. /buybook - is matched agaist the BookPurchase servlet. (processed by web.xml)
5. /proApache - is processed by the servlet (processed by the servlet)
Advanced Tomcat features
The list below contains some of the more common used advanced features of the tomcat server

Access log administration
Request Filtering
Single sign-on across web application
JNDI and JBDC
Realms

Valves are used to intercept clients requests (see fig 1), these components are placed inside the <engine>, <host> or <context>.
The standard valves are:

Access logging	Enable the logging of requests
Single sign-on	Enhance the user experience by requesting for the password only once.
Request Filtering	Enable selective filtering of incoming request based on IP or hostname
Request Dump	Prints the headers and cookies of incoming requests and outgoing responses to a log

JNDI and JDBC is a API used for looking up information either from a Directory service or a Database.
Realms help web application developers in implementing and enforcment of specific security policies.
Class loaders
When a java class is instantiated as an object, that class must be loaded into memory. There are three distinct class loaders:

bootstrap	This class loader is used by JVM to load those java classes that are necessary for the JVM to function. It is responsible for loading all Java core classes.
extension	Is repsonsible for loading all the classes in one or more extension directories. The extension directory on sun's JVM is /jdk/jre/lib/ext.
system loader	This loader locates its classes in those directories and JAR files specified in the CLASSPATH enviroment variable.

When a class is required to be loaded it is normally delegated to the parent to fulfil the request. So the bootstrap loader will try to fulfil first and then the extension loader and lastly the system loader.
None of the above class load preload all classes in there search paths but perform what is know as lazy loading in other words it will only load the class when requested, this allows for faster performance, efficiency and flexbility.
Tomcat Class loaders
Tomcat build on the Java class loaders by adding its own class loaders.

Common class loader	Loads classes that are used by Tomcat and are also pubicly available to all web applications Locations: $CATALINA_HOME/common/lib $CATALINA_HOME/common/classes
Catalina class loader	Loads all Tomcat classes that are only specific to Tomcat (that is not publicly defined API's an so on) Locations: $CATALINA_HOME/server/lib $CATALINA_HOME/server/classes
Shared class loader	This is were you place your own public classes Locations: $CATALINA_HOME/shared/lib $CATALINA_HOME/shared/classes
Web App class loader	This is were each web application loads its own classes Locations: $CATALINA_HOME/webapps/<webapp>/WEB-INF/lib $CATALINA_HOME/webapps/<webapp>/WEB-INF/classes

An important note is that the web application class loader does not use the delegation process that class loaders are encouraged to use. Instead, it tries to load classes first before the delegation. This allowsweb application to override classes in the shared and common class loaders on a per-web application basis.
HTTP connectors
The HTTP connectors are Java classes that implement the HTTP protocol. The connector class has code to parse the HTTP request and take the required action of either serving up static content or passing the request through the Tomcat servlet engine.
The default HTTP/1.1 coyote connect below shows the class used and the port number that tomcat listens for cleint requests, the min/max processors specifies the request processing threads basically start with 5 and maximum running would be 75. enable lookup resolves the IP address via DNS (turn this off for a increase in performance). If any request come in that are notHTTP/1.1 they will be redirected to port 8443. The rest of the option are self explaining.
<Connector className="org.apache.coyote.tomcat4.CoyoteConnector"
                    port="8080"
                    minProcessors="5"
                    maxProcessors="75"
                    enableLookups="true"
                    redirectPort="8443"
                    acceptCount="100"
                    debug="0"
                    connectionTimeout="20000"
                    useURIValidationHack="false"
                    disableUploadTimeout="true" />
AJP Connector
The apache JServ protocol is a packet-orientated TCP/IP based protocol. It provides comunication between the apache web server process and the running tomcat instances. The are various version of the AJP protocol connector 1.2, 1.3 (commonly used) and 1.4.
Some noticeable features of AJP 1.3 are:

Good Performance
Support for SSL
The factility to get information about encryption and client certificates.

The mod_jk module is the component that will redirect all clients requests to the tomcat server.
The Workers
A worker is a Tomcat instance that is running to serve JSP/Servlet requests coming from another web server. There can be many workers whcih could be used to load balance the requests especially a heavy loaded site.
The file workers.properties consists of entries that will convey information to the web server plug-in about any available workers. When load balancing a worker is created that uses a weighted round-robin alogritham for load balancing with support for seamless sessions. The loadbalance worker will redirect traffic to other available workers. This has the added bonus that if one worker was to offline the remaining workers still serve the requested JSP/Sevlets requests.
The worker.properties file below creates two workers and a load balancing worker which uses the two workers to balance load. The lbfactor can be adjusted to proportionally distribute the load, this may be used when one server is more powerful than the other server or if one server is more heavy loaded than other.

# Tomcat Worker 1
worker.tomcat1.port=8009
worker.tomcat1.host=localhost
worker.tomcat1.type=ajp13
worker.tomcat1.lbfactor=10
worker.tomcat1.cachesize=5
# Tomcat Worker 2
worker.tomcat2.port=8010
worker.tomcat2.host=localhost
worker.tomcat2.type=ajp13
worker.tomcat2.lbfactor=10
worker.tomcat2.cachesize=5
# Load Balancer Worker
worker.loadbalancer.type=lb
worker.loadblancer.blanced_workers=tomcat1, tomcat2

10-unique-and-amazing-places-on-earth

noreply@blogger.com (Anonymous) — Sun, 15 May 2011 09:07:00 +0000

After seeing “10 More Amazing Wonders of the Natural World”, which many contained places I had never even heard of, I was inspired to make my own list. This list differs from the previous in that it contains things which may not be stunning to behold, but are unique for their size, location, or natural impact.

The Door To Hell

Turkmenistan

The Door to Hell, as local residents at the nearby town of Darvaza have dubbed it, is a 70 meter wide crater in Turkmenistan that has been burning continuously for 35 years. In 1971, geologists drilling for gas deposits uncovered a huge underground cavern, which caused the ground over it to collapse, taking down all their equipment and their camp with it. Since the cavern was filled poisonous gas, they dared not go down to retrieve their equipment, and to prevent the gas escaping they ignited it, hoping it would burn itself out in a couple of days. Unfortunately, there was a slight miscalculation as to the amount of gas that was trapped, and the crater continues to burn to this day.

You can see it on Google Earth at 40°15′8″N 58°26′23″E

Mount Roraima

Venezuela, Brazil and Guyana

Mount Roraima is a pretty remarkable place. It is a tabletop mountain with sheer 400-metre high cliffs on all sides. There is only one ‘easy’ way up, on a natural staircase-like ramp on the Venezuelan side – to get up any other way takes and experienced rock climber. On the top of the mountain it rains almost every day, washing away most of the nutrients for plants to grow and creating a unique landscape on the bare sandstone surface. This also creates some of the highest waterfalls in the world over the sides (Angel falls is located on a similar tabletop mountain some 130 miles away). Though there are only a few marshes on the mountain where vegetation can grow properly, these contain many species unique to the mountain, including a species of carnivorous pitcher plant.

Meteor Crater

USA

Meteor Crater is a meteorite impact crater located approximately 43 miles (69 km) east of Flagstaff, near Winslow in the northern Arizona desert of the United States. Because the US Department of the Interior Division of Names commonly recognizes names of natural features derived from the nearest post office, the feature acquired the name of “Meteor Crater” from the nearby post office named Meteor. The crater was created about 50,000 years ago during the Pleistocene epoch when the local climate on the Colorado Plateau was much cooler and damper. At the time, the area was an open grassland dotted with woodlands inhabited by woolly mammoths, giant ground sloths, and camels. It was probably not inhabited by humans; the earliest confirmed record of human habitation in the Americas dates from long after this impact. The object that excavated the crater was a nickel-iron meteorite about 50 meters (54 yards) across, which impacted the plain at a speed of several kilometers per second.

The Great Dune of Pyla

France

Since Europe has no deserts, you’d think the title of “Europe’s largest sand dune” would go to something that wasn’t particularly impressive. But you’d be wrong. The Great Dune of Pyla is 3km long, 500m wide and 100m high, and for reasons I will probably never understand, it seems to have formed in a forest. The dune is very steep on the side facing the forest and is famous for being a paragliding site. At the top it also provides spectacular views out to sea and over the forest (since the dune is far higher than any of the trees surrounding it).

Socotra

Republic of Yemen

Socotra has been described as one of the most alien-looking place on Earth, and it’s not hard to see why. It is very isolated with a harsh, dry climate and as a result a third of its plant-life is found nowhere else, including the famous Dragon’s Blood Tree, a very-unnatural looking umbrella-shaped tree which produces red sap. There are also a large number of birds, spiders and other animals native to the island, and coral reefs around it which similarly have a large number of endemic (i.e. only found there) species. Socotra is considered the most biodiverse place in the Arabian sea, and is a World Heritage Site.

83-42

Greenland

This is more of a curiosity and not visually impressive, but 83-42 is believed to be the northernmost permanent point of land on earth. It is tiny, only 35m by 15m and 4m high, but is about 400 miles from the north pole. It beat the previous record holder, ATOW1996, when it was discovered in 1998, and lichens were found growing on it, suggesting it was not just one of the temporary gravel bars that are found in that region, which are regularly pushed around by the rough seas. The picture above features what is currently the northernmost point on land, one of the temporary gravel bars, photographed in 2007, as I could find no photos of 83-42 (For some reason, nobody feels the need to produce a photograph of a tiny rock in the middle of nowhere, which only five people have ever stepped foot on).

Rotorua

New Zealand

Rotorua is a city on the southern shores of the lake of the same name, in the Bay of Plenty region of the North Island of New Zealand. The city is known for its geothermal activity, with a number of geysers, notably the Pohutu Geyser at Whakarewarewa, and boiling mud pools (pictured above) located in the city. This thermal activity owes itself to the Rotorua caldera on which the city lies. Rotorua is also a top adventure destination and is New Zealand’s Maori cultural heartland. Rotorua city is renowned for its unique “rotten eggs” aroma, which is caused by the geothermal activity releasing sulphur compounds into the atmosphere. If you are ever visiting New Zealand – this is a city you must see. It was once home to the famed Pink and White Terraces and you can visit thermal wonderlands with sights that are truly astounding.

Don Juan Pond

Antarctica

With a salinity of over 40%, Don Juan Pond is the saltiest body of water in the world. It is named after the two pilots who first investigated the pond in 1961, Lt Don Roe and Lt John Hickey. It is a small lake, only 100m by 300m, and on average 0.1m deep, but it is so salty that even in the Antarctic, where the temperature at the pond regularly drops to as low as -30 degrees Celsius, it never freezes. It is 18 times saltier than sea water, compared to the Dead Sea which is only 8 times saltier than sea water.

Iceberg B-15

Antarctica

Iceberg B-15 was the largest ever recorded iceberg. It had an area of 3,100 km², making it larger than the island of Jamaica, and was created when part of the Ross Ice Shelf broke off in March 2000. In 2003, it broke apart, and one of the larger pieces (called B-15a) drifted north, eventually smashing into a glacier in 2005, breaking off an 8-km² section and forcing many antarctic maps to be rewritten. It drifted along the coast and eventually ran aground, breaking up once again. In 2006, a storm in Alaska (that’s right, Alaska) caused an ocean swell that travelled 13,500km, over 6 days, to Antarctica and broke up the largest remaining part even more. Almost a decade on, parts of the iceberg have still not melted, with the largest remaining part, still called B-15a, having an area of 1,700 km². The picture above shows B-15a (top left) in 2005, after drifting west into the Drygalski Glacier (bottom), breaking the end off into several pieces.

Guaíra Falls

Brazil-Paraguay border

Located on the Parana river the Guaíra Falls were, in terms of total volume, the largest waterfall on earth. 1,750,000 cubic feet of water fell over this waterfall each second on average, compared to just 70,000 cubic feet per second for Niagra Falls. However, the falls were flooded in 1982 when a dam was created to take advantage of this massive flow rate. The Itaipu Dam is now the second most powerful hydroelectric dam in the world, after the Three Gorges Dam. The Itaipu Dam supplies 90% of the power consumed by Paraguay, and 19% of the power consumed by Brazil, including Rio de Janeiro and São Paulo.

15-resume-blunders-to-avoid

noreply@blogger.com (Anonymous) — Sun, 15 May 2011 09:03:00 +0000

Most articles on this topic list blunders that very few people are dumb enough to actually make. Maybe we’re making a bold assumption, but it’s not likely that very many people are “stating that they work well in the nude”, as one resume blunder article cautions against. Nor are very many job seekers likely to “use pale blue paper with teddy bears printed around the border”, as another article warns of. Very helpful! But nevertheless, there are quite a few realresume blunders that perfectly intelligent people commit, which you should be aware of, because they can diminish you in the eyes of employers.

1. Letting typos slip through

Possibly the easiest resume blunder to make, letting typos slip through is almost one of the most dangerous. A recent survey indicated that 84% of hiring personnel toss a resume in trash upon spotting just one or two typos! Understand this for what it is: the HR people do not have some type of vendetta against spelling errors in and of themselves. Rather, what they see when they come across as a spelling error is a lack of conscientiousness. They see someone who apparently did not even take their application seriously enough to proofread it before clicking the “Send” button or mailing it in. This isn’t the impression you want to give off, so be sure to eliminate all spelling errors before submitting your resume.

2. Inappropriate e-mail address

It is common today for applicants to leave an e-mail address on their resumes. Nothing wrong with that. Unfortunately, many applicants make the mistake of leaving personal or inappropriate e-mail addresses rather than professional ones. Put yourself into the HR guy’s shoes. You are looking at two very impressive applications, but one them lists their e-mail as “ismokeweedeveryday@gmail.com” while the other lists theirs as “JohnSmith@gmail.com.” Which person are you more likely to hire? If you don’t already have a professional-sounding e-mail address, just visit one of the many free e-mail providers (like gmail, yahoo, and hotmail) and sign up for one.

3. Listing irrelevant, non-job-related information

Too many applicants try to get “cute” and show how eclectic they are by listing non-job related information in their resumes. This can be anything from the vacations they’ve taken, the hobbies they enjoy, or even (in rarer cases) the pets they own! It’s understandable to want to “liven up” your application, but remember this: the HR person who will eventually read it reads thousands of applications each year. They have trained themselves to relentlessly skim through applications searching for only the very relevant details.

4. Poor formatting

Remember: employers and their HR staffs scan resumes. They do not painstakingly read each and every word. Being that this is the case, the best thing you can do is make your resume scannable. This means using one of the many free resume templates that come with Word or that can be downloaded on the Internet. These are the formats employers are used to reading, and it’s one easy way you can take friction and hassle out of their reviewing of your resume. Don’t get “cute” with formatting!

5. Use of personal pronouns

Remember back in college when your professor didn’t let you use words like “I” or “me” in essays? Keep this rule in mind when creating your resume as well. Like a college essay, a resume is a formal document (albeit a business document rather than an academic one.) For example, rather than saying

I oversaw the creation of a new department that generated $5 million in sales and increased pre-tax profits by 15%.

Say this instead:

Oversaw creation of new department that generated $5 million in sales and increased pre-tax profits by 15%.

If this seems like a lot to remember, just pretend that you are someone else, describing yourself to another person. This rule will help keep you on track.

6. Trying to sound “well-rounded”

Some applicants believe they will look better to employers if they seem well-rounded. Such people typically play up how many committees they’ve served on, how many different and varying job titles they’ve held, different industries they’ve worked in, and the like. Unfortunately, this does not work as intended. Most employers see such people as not being great at any one thing, and they are thus unsure of how to evaluate them. Most often, such applicants are simply passed over in favor of those with more specific skillsets.

7. Self-deprecation

Too many resumes have self-deprecating remarks and phrases. While it’s understandable to not want to be seen as bragging on your application, you still want to look good. It is for this reason that statements like “graduated in the top 66% of my class” and “self-employment: what a disaster that was!” will not make you look good. Rather, they will make you seem like a potential threat to the organization, someone who probably shouldn’t be trusted with much power or autonomy.

8. Bragging

Of course, the other side of the resume blunder coin are applicants who excessively brag about themselves or their achievements. Again – you do want your resume to make you look like a strong candidate. What you do not want is obnoxious arrogance, as seen in statements like “you will never find a better candidate than me”, or “my job performance is unsurpassed”, or “if you don’t hire me, you’ll regret it!” Such statements make you seem cocky and indicate a potential lack of team spirit (or even narcissism!)

9. Focusing on responsibilities instead of achievements

The best resumes draw attention to what you as an employee have achieved – sales growth, cost-cutting, higher customer retention, etc. The worst resumes talk only or mostly about what responsibilities you have held – manager, committee supervisor, etc. Take a good, hard look at your resume and determine if it is primarily responsibilities or achievements based. If it is not already achievements-based, make sure it is before you send it in to employers!

10. Important skills buried at the bottom

Some otherwise good resumes handicap themselves by listing important skills at the bottom – say, computer skills. It should go without saying that the skills most relevant to the job you want should be listed top, front, and center in your resume. Read over your resume a few times and put yourself in the position of a busy, beleaguered HR person. Would your job-specific skills jump out to them? If not, re-arrange your resume so that they will.

11. Lack of bullet points

As alluded to earlier, scanability is essential to creating a good resume. One of the most critical elements of scanability is the use of bullet points. Do not make the mistake (which many applicants do) of writing everything in as a “wall” of text, hoping that whomever reads your resume will painstakingly peruse your every word to extract the important parts. They will not. That being the case, be sure to use bullets early and often!

12. Listing references directly on the resume

You should list your references on a separate sheet of paper or, ideally, only provide them when asked. Including them within the resume itself only adds bulk (which makes it more tempting to rush through) and does you little good, since references will only matter if and when the employer decides to interview you and advance the process beyond the resume-reviewing stage. When in doubt, leave the references out!

13. The “more is better” mentality

An article listing the 100 funniest resume mistakes says that one woman divided her resume into acts as though it were a play: ie, Act 1 of the resume, Act 2 of the resume, etc. We realize this is rather extreme and ridiculous, but it’s telling because of how many people (albeit less dramatically) adopt a “more is better” approach with their resumes. This is absolutely false. In fact, research would probably show that resumes are read less often in proportion to how large they are. Whenever possible, try to include only the essential details necessary to convey your main point.

14. Resume sent as an attachment without you knowing how it’ll look

We’ve all been there: you send something out as an e-mail attachment, only to have it look different (sometimes drastically) on your recipient’s computer than it does on yours. This can be disastrous if the random factor and chaos of the Internet messes up your resume’s formatting or bullets! Luckily, this need not become an obstacle. Before sending your resume via e-mail, simply “test” send it to a few of your friends and verify how it looks on their computers. If it looks as it does on your computer, send it to the employer. If not, find out why and fix it.

15. Passive-aggressiveness

Not every job applicant has the benefit of writing a resume with a sparkling job history. Some have been fired numerous times or been involved in conflicts with bosses at one or more jobs. There is a strong tendency among such people to demonize their ex-bosses in the resume, blaming them for their own failures. But while you might think this makes you look better, it rarely has this effect. Rather, most employers will read something like “I only got fired because my boss was an unrealistic jerk” and imagine themselves being in that boss’ shoes someday. You will be seen as a “problem-person” and probably ignored. The far more effective and mature approach is to simply acknowledge any past difficulties you may have had and exude an honest, sincere willingness to put those things behind you.

humor-phrases-used-to-improve-your-resume

noreply@blogger.com (Anonymous) — Sun, 15 May 2011 09:01:00 +0000

REASONS FOR LEAVING THE LAST JOB:

Responsibility makes me nervous.
They insisted that all employees get to work by 8:45 every morning. Couldn’t work under those conditions.
Was met with a string of broken promises and lies, as well as cockroaches.
I was working for my mom until she decided to move.
The company made me a scapegoat – just like my three previous employers.

JOB RESPONSIBILITIES:

While I am open to the initial nature of an assignment, I am decidedly disposed that it be so oriented as to at least partially incorporate the experience enjoyed heretofore and that it be configured so as to ultimately lead to the application of more rarefied facets of financial management as the major sphere of responsibility.
I was proud to win the Gregg Typting Award.

SPECIAL REQUESTS & JOB OBJECTIVES:

Please call me after 5:30 because I am self-employed and my employer does not know I am looking for another job.
My goal is to be a meteorologist. But since I have no training in meteorology, I suppose I should try stock brokerage.
I procrastinate – especially when the task is unpleasant.

PHYSICAL DISABILITIES:

Minor allergies to house cats and Mongolian sheep.

PERSONAL INTERESTS:

Donating blood. 14 gallons so far.

SMALL TYPOS THAT CAN CHANGE THE MEANING:

Education: College, August 1880-May 1984.
Work Experience: Dealing with customers’ conflicts that arouse.
Develop and recommend an annual operating expense fudget.
I’m a rabid typist.
Instrumental in ruining entire operation for a Midwest chain operation.

9 Extraordinary Human Abilities

noreply@blogger.com (Anonymous) — Sun, 15 May 2011 08:56:00 +0000

This list of extraordinary human abilities was inspired The Top 10 Tips to Improve Your Memory when I began thinking about how some people are blessed (or cursed, depending on your point of view) with the ability to recall a scene as if they were looking at a photograph. And how other people can recreate music from memory, such as Mozart’s famed reproduction of Gregorio Allegri’s Miserere after one hearing. What other extraordinary abilities might humans have? I’ve listed nine of the most well understood (i.e. not paranormal or ‘fringe science’) and interesting abilities rated from most common to most interesting and rare. Bear in mind that most of these unusual abilities are genetic and cannot be controlled by the person affected but are an inherent quality of their physical self.

Supertasters

People who experience taste with greater intensity than the rest of the population are called supertasters. Having extra fungiform papillae (the mushroom shaped bumps on the tongue that are covered in taste buds) is thought to be the reason why these people have a stronger response to the sensation of taste. Of the five types of taste, sweet, salty, bitter, sour, and umami, a supertaster generally finds bitterness to be the most perceptible.

Scientists first noticed the differing abilities of people to taste a known compound when a DuPont chemist called Arthur Fox asked people to taste Phenylthiocarbamide (PTC). Some people could taste its bitterness; some couldn’t – whether people could depended on their genetic make-up (a variant of this test is now one of the most common genetic tests on humans). While about 70% of people can taste PTC, two thirds of them are rated as medium and only one third (approximately 25% of the wider population) are supertasters.

Supertasters will often dislike certain foods, particularly bitter ones, such as brussel sprouts, cabbage, coffee, and grapefruit juice. Women, Asians, and Africans are most likely to have the increased number of fungiform papillae that make them supertasters.

Absolute pitch

People with absolute pitch are capable of identifying and reproducing a tone without needing a known reference. It is not simply a better ability to hear but the ability to mentally class sounds into remembered categories. Examples of this include identifying the pitch of everyday noises (e.g. horns, sirens, and engines), being able to sing a named note without hearing a reference, naming the tones of a chord, or naming the key signature of a song. Doing any of these is a cognitive act – it requires one to remember the frequency of each tone, be able to label it (e.g. ‘A’, ‘C#’, or ‘F-flat’), and sufficient exposure to the range of sound within each label. Opinions vary as to whether absolute pitch is genetic or a learned ability that is strongly influenced to one’s exposure to music at crucial developmental stages – much like how a child’s ability to identify colors by their frequency depends on the type and level of their exposure to it.

Estimates of the portion of the population having absolute pitch range from 3% of the general population in the US and Europe to 8% of those (from the same areas) who are semi-professional or professional musicians. In music conservatories in Japan however, about 70% of musicians have absolute pitch. Part of the reason for this significantly larger percentage may be because absolute pitch is more common among people who grew up in a tonal (Mandarin, Cantonese, and Vietnamese) or pitch accent (Japanese) language environment. Absolute pitch is also more common in those who are blind from birth, have William’s Syndrome, or have an autism spectrum disorder.

Tetrachromacy

Tetrachromacy is the ability to see light from four distinct sources. An example of this in the animal kingdom is the zebrafish (Danio rerio), which can see light from the red, green, blue, and ultraviolet sections of the light spectrum. True tetrachromacy in humans is much rarer however – according to Wikipedia only two possible tetrachromats have been identified.

Humans are normally trichromats, having three types of cone cells that receive light from either the red, green, or blue part of the light spectrum. Each cone can pick up about 100 graduations of color and the brain combines colors and graduations so that there are about 1 million distinguishable hues coloring your world. A true tetrachromat with an extra type of cone between red and green (in the orange range) would, theoretically, be able to perceive 100 million colors.

Like supertasting, tetrachromacy is thought to be much more common in women than men – estimates range from 2 – 3% to 50% of women. Interestingly, colour-blindness in men (much more common than in women) may be inherited from women with tetrachromacy.

Echolocation

Echolocation is how bats fly around in dark forests – they emit a sound, wait for the echo to return, and use that sound of the echo in each ear plus the return time to work out where an object is and how far away. Surprisingly (well, maybe not on this list!), humans are also capable of using echolocation. Use of echolocation is probably restricted to blind people because it takes a long time to master and heightened sensitivity to reflected sound.

To navigate via echolocation a person actively creates a noise (e.g. tapping a cane or clicking the tongue) and determines from the echoes where objects are located around them. People skilled at this can often tell where an object is, what size it is, and its density. Because humans cannot make or hear the higher pitched frequencies that bats and dolphins use they can only picture objects that are comparatively larger than those ‘seen’ by echolocating animals.

People with the ability to echolocate include James Holman, Daniel Kish, and Ben Underwood. Perhaps the most remarkable and well-documented of cases is the story of Ben Underwood, who lost both his eyes to retinal cancer at the age of three. He is shown in the video above (warning: the scene where he puts in his prosthetic eyeballs may be a bit disturbing for some).

Genetic Chimerism

In the Iliad Homer described a creature having body parts from different animals, a chimera, from this mythological monster comes the name of the genetic equivalent – chimerism. Genetic chimerism, or tetragametism, in humans and other animals happens when two fertilized eggs or embryos fuse together early in pregnancy. Each zygote carries a copy of its parents DNA and thus a distinct genetic profile. When these merge, each population of cells retains its genetic character and the resulting embryo becomes a mixture of both. Essentially, a human chimera is their own twin.

Chimerism in humans is very rare; Wikipedia states that there are only about 40 reported cases. DNA testing is often used to establish whether a person is biologically related to their parents or children and can uncover cases of chimerism when DNA results show that children are not biologically related to their mothers – because the child inherited a different DNA profile to the one shown by a blood test. This is what happened in the case of Lydia Fairchild: DNA tests of herself and her children led the state to think that she was not actually their mother.

People born with chimerism typically have immune systems that make them tolerant to both genetically distinct populations of cells in their body. This means that a chimera has a much wider array of people to choose from should they need an organ transplant.

Synesthesia

Imagine consistently associating numbers or letters with certain colours, or hearing a specific word which triggers a particular sensation of taste on your tongue. These are two forms of a neurological condition called synesthesia. Synesthesia is when stimulation of a particular sensory or cognitive pathway leads to an involuntary (i.e. synesthesia is not learnt) response in other sensory or cognitive pathways.

Synesthesia is most often genetic and the grapheme (letters, numbers, or other symbols) to colour form of synesthesia is the commonest. Other synesthetes can experience special-sequence synesthesia (e.g. where dates have a precise location in space), ordinal linguistic personification (when numbers have personalities), or sound to colour synesthesia (where tones are perceived as colours).

Although synesthesia is a neurological condition it shouldn’t be thought of as a disorder, because generally it does not interfere with a person’s ability to function. Most people are not even aware that their experiences of life elicit more sensory responses than other peoples might and the ones that are rarely consider synesthesia to have a negative impact on their lives.

Predictions of the percentage of people with synesthesia vary widely, from 1 in 20 to 1 in 20,000. Studies from 2005 and 2006, using a random population sample, suggested 1 in about 23 people have synesthesia. Examples of people with synesthesia include the author Vladimir Nabokov, composer Olivier Messiaen, and scientist Richard Feynman. Daniel Tammet, who is mentioned in the next section of this list, is a synesthete (in addition to being a mental calculator) who sees numbers with shapes and texture.

Mental calculators

The most extraordinary group of people adept at performing complex mental calculations is those who are also autistic savants. While there are many trained people who can work out multiplications of large numbers (among other calculations) in their head extremely fast – mostly mathematicians, writers, and linguists – the untrained ability of autistic savants is the most interesting. The majority of these people are born with savant syndrome (only an estimated 50% of people with savantism are also autistic), which is still poorly understood, few develop it later in life, usually due to a head injury.

There are less than 100 recognised prodigious savants in the world and of the savants with autism who are capable of using mental calculation techniques there are even less. Recent research has suggested that a blood flow to the part of the brain responsible for mathematical calculations of six to seven times the normal rate is one of the factors that enables mental calculators to work out math much faster than the average person.

Examples of people with extraordinary calculation skills include Daniel McCartney, Salo Finkelstein, and Alexander Aitken. Daniel Tammet is one of few who are also autistic savants.

Eidetic memory

When a person has photographic memory or total recall this is called eidetic memory. It is the ability to recall sounds, images, or objects from one’s memory with extreme accuracy. Examples of eidetic memory include the effort of Akira Haraguchi who recited from memory the first 100,000 decimal places of pi and the drawings of Stephen Wiltshire (who is also an autistic savant) – his recreation of Rome is shown in the video above. Kim Peek, the inspiration for the autistic (Peek is not actually autistic though) character of Raymond Babbit in the movie Rainman, also possesses eidetic memory – among other things he can recall some 12,000 books from memory.

Whether true photographic memory exists in adults is still a controversial issue, but it is accepted that eidetic abilities are distributed evenly between men and women. One also cannot become an eidetiker through practice.

Immortal cells

There is only one known case of a person having immortal cells (cells that can divide indefinitely outside of the human body, defying the Hayflick Limit) and that is of a woman named Henrietta Lacks. In 1951, 31 year old Henrietta Lacks was diagnosed with cervical cancer, which she died from within the year. Unknown to her and her family (i.e. without informed consent) a surgeon took a tissue sample from her tumor that was passed on to a Dr. George Gey. A scientist for the John Hopkins University Tissue Culture Laboratory, Gey propagated Lacks’ tissue sample into an immortal cell line – the HeLa cell line (pictured above). The cells from Lacks’ tumour have an active version of the telomerase enzyme (telomerase is the mechanism by which cells age or are aged) and proliferate abnormally fast. On the day of Henrietta Lacks’ death, Dr. Gey announced to the world that a new age in medical research had begun – one that might provide a cure for cancer.

HeLa cells were utilised in 1954 by Jonas Salk to develop the cure for polio. Since then they’ve been used in researching cancer, AIDS, the effects of radiation and toxic substances, and for mapping genes, among other things.

Today, the HeLa cells are so common in laboratories that they contaminate many other cell cultures and have rendered some biological studies invalid through their presence. There are also more HeLa cells alive today than when Henrietta Lacks was alive – they outweigh her physical mass by many times. Tragically, Lacks was never told of the immensely valuable contribution her cells made to science and her family was not informed until many years later that her cells were being used for research purposes (a 1990 court ruling later verified Lacks’ hospital as the owner of her discarded tissue and cells). I highly recommend reading this story for a better picture of Henrietta Lacks’ life and the consequences of her cancer.

40 Romantic Photographs Shot in the Rain

noreply@blogger.com (Anonymous) — Sun, 15 May 2011 08:50:00 +0000

40 Romantic Photographs Shot in the Rain

After preparing all the equipment for an outdoor shoot but suddenly a heavy rain came. Most photographers will feel uncomfortable and choose to stay home then. Pictures taken in the rain can actually look very soft and romantic. Let us admire these beautiful images taken by the skillful photographers.

source :source :http://10steps.sg/inspirations/photography/40-romantic-photographs-shot-in-the-rain/#1