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Manipal University - MS (CS) study notes

2012-02-01T09:39:00.003+05:30

These study notes are based on the previous year question papers. In case you are in hurry, this may help you at the last moment. good luck for your preparations. Want to know more about the course ?? Here is the link you should visit Master of Science(MS) Program, Manipal University

Signing your code - security in java

2011-05-05T08:41:00.000+05:30

Collections API - Taken from Java Tutorial

2011-05-05T08:20:00.000+05:30

Some of the important features of Collections!!

Source : http://download.oracle.com/javase/tutorial/collections/interfaces/collection.html

Collection Interface Bulk Operations

Bulk operations perform an operation on an entire Collection. You could implement these shorthand operations using the basic operations, though in most cases such implementations would be less efficient. The following are the bulk operations:
containsAll — returns true if the target Collection contains all of the elements in the specified Collection.

addAll — adds all of the elements in the specified Collection to the target Collection.

removeAll — removes from the target Collection all of its elements that are also contained in the specified Collection.

retainAll — removes from the target Collection all its elements that are not also contained in the specified Collection. That is, it retains only those elements in the target Collection that are also contained in the specified Collection.

clear — removes all elements from the Collection.

The addAll, removeAll, and retainAll methods all return true if the target Collection was modified in the process of executing the operation.As a simple example of the power of bulk operations, consider the following idiom to remove all instances of a specified element, e, from aCollection, c.
c.removeAll(Collections.singleton(e));
More specifically, suppose you want to remove all of the null elements from a Collection.
c.removeAll(Collections.singleton(null));
This idiom uses Collections.singleton, which is a static factory method that returns an immutable Set containing only the specified element.

Good presentation on Division Operator

2011-05-01T09:33:00.002+05:30

This is the nice presentation explaining how to implement the Division operator in SQL.

Click here for the presentation

Search in Active directory in Windows 7

2011-03-25T17:53:00.001+05:30

In Windows 7, if I want to open the above screen, now I need to run the following command.

%SystemRoot%\SYSTEM32\rundll32.exe dsquery,OpenQueryWindow

Earlier, in XP, it was so simple - Start>>Search for People option used to give it.

Spring JDBCTemplate

2011-01-23T00:36:00.001+05:30

Check out this SlideShare Presentation:

Spring JDBCTemplate

View more presentations from Guo Albert.

UML Presentation - Very nice

2010-09-11T11:54:00.002+05:30

UML PPT

Virtual Private LAN Service (VPLS)

2010-09-08T19:12:00.004+05:30

A Virtual Private LAN Service (VPLS) [VPLS] is used to interconnect systems across a wide-area or metropolitan-area network, making it appear that they are on a private LAN. The systems which are interconnected may themselves be LAN switches. If, however, they are IP hosts or IP routers, certain simplifications to the operation of the VPLS are possible. We call this simplified type of VPLS an "IP-only LAN Service" (IPLS).

In an IPLS, as in a VPLS, LAN interfaces are run in promiscuous mode, and frames are forwarded based on their destination MAC addresses. However, the maintenance of the MAC forwarding tables is done via signaling, rather than via the MAC address learning procedures specified in [IEEE 802.1D].

My XML Learning Forum

2010-08-30T11:50:00.000+05:30

Image by ƷƋĐEL ♥ via FlickrAfter a long time, I referred one of the forums created by me while I was facilitating XML sessions. This was very useful. Have a look when you have time. Today, I closed it for further post. I have planned that this can be shared to future learners.
http://mbait.forumotion.net/

XML Overview quiz

2010-08-30T10:51:00.001+05:30

XML Overview » ProProfs Quizzes

How to save all the files in UTF-8 format in TextPad

2010-06-25T12:04:00.001+05:30

If you want to setup the default encoding as UTF-8 in TextPad, here is the screenshot that you can refer.

Go to Configure->Preferences -> Document Classes -> Default

Under Default encoding: select UTF-8

Why you need to do this?

We want to search some content in a file and gave a search in some root folder. I found that content , say , in 100 files. I want to replace all those characters with some special characters. So, I opened all the files by using Open All command.

Then, Using Replace All in all the Open files, i did the change. Now, I would use Save All option. This will try to save all the files as per the Default encoding. So, if you have not set the default encoding to UTF-8, it will not be possible to save all the files in the UTF-8 encoding in one shot.

Note that, when you open a file or save a file, you definitely get the option to save as in desired format. But, the above is applicable when you want to do a bulk save in desired format.

This is how you save all the files in UTF-8 format in one shot using Save All option

Note : As of TextPad 4.7.0, The default encoding for a document class can now be set to UTF-8. This affects new documents and when the encoding of existing documents is ambiguous. UTF-8 can also be chosen when opening a file with the File Open command. Source:http://www.textpad.com/support/relnotes.html

[Update - July 20, 2010] - Finally, I found an easy way - Edit Plus has the option to achieve the same for single as well as multiple file. Please use that.

m2eclipse and subeclipse - eclipse plugin demo

2010-06-14T00:11:00.000+05:30

Adding JDBCTemplate to your STRUTS2 and SPRING Project - 2

2010-06-12T21:51:00.001+05:30

Adding JDBCTemplate to your STRUTS2 and SPRING Project - 1

2010-06-12T21:38:00.003+05:30

Eclipse Overview

2010-05-15T20:55:00.001+05:30

Check out this SlideShare Presentation: What I liked most is the way presentation is organized here.

Eclipse Overview

View more presentations from Lars Vogel.

Finding Width and Height of an Image in Java

2010-02-20T22:33:00.002+05:30

Requirement:

Images need to be inserted in the body (say an article body content) - we have the image files (JPG). So, we will add the IMG tag as the prefix to the body content. But, some image size (width) is more that will break the target system. Now, we need to add the height and width attribute to the above tag. But, the important thing here is that - we need to know the current dimensions of the image (physical file). Then, if the dimensions are within the limit that the target system allow - simply add it using HTML DOM API. Otherwise, if the width is more than expected, fix it to the max and reduce the height in the same ratio and then the new height and width can be added to the img tag.

Now, I used the below code (originally posted at http://www.java.happycodings.com/Java_AWT/code28.html ) - it was simple and worked for me - i tried on JPG images. Hope it works for GIF as well.

import java.awt.*;
import javax.swing.*;

public class ImageXY
    {
     public static void main(String[] args)
         {
       
         Image image = Toolkit.getDefaultToolkit().getImage("test.jpg");
         ImageIcon icon = new ImageIcon(image);
         int height = icon.getIconHeight();
         int width = icon.getIconWidth();
         System.out.println("height"+height);
         System.out.println("width"+width);
     }
}

Advantages on having a master DB script

2009-11-23T11:34:00.002+05:30

Image via Wikipedia

Many a time we require to execute more than one SQL scripts. In this kind of scenario, we should create one master script and call all other scripts from inside it.

Reference : Using SQLCMD to Execute Multiple SQL Server Scripts

This helps in-

- Any non-technical user can also execute it
- In Oracle, if you run the DDL in between DML, the auto commit feature gets executed, that is not expected. If we have one master script, we can define the order in which they should get executed.
- We should also have the corresponding script to revert the operations.

How to Insert Code Snippet on Blogger

2009-11-17T09:00:00.001+05:30

I used Syntaxhighlighter to insert code snippet in Blogger.

Found the article on this blog. Followed the steps and was able to do. Thought of sharing this with all of you. How to Insert Code Snippet on Blogger

I uploaded all my code to Google Sites

Sample Code in java to test

interface Operation {
 double apply(double x, double y);
}

Good Practices for a tech paper

2009-11-17T06:45:00.000+05:30

Notes from a session attended - What goes in writing a tech paper.

Summary:
1. Tech paper can have three major sections called : Introduction, body and conclusion

2. The paper should have a good continuity when the reader goes through the sections from introduction to conclusion.

3. Use simple English/language. Don’t use complex or lengthy statements.

4. It will be good if you bring in your opinion than just present facts (just facts make it look like a tech manual). At the same time, don’t make the paper too opinionated (it will look like a blog).

5. Paper should be like a mini-story of the subject/opinion/context what you are trying to articulate.

6. Any content you are pulling from other books/websites should be explicitly highlighted and should have a proper reference. It will show you have done some research.

7. Maintain a good balance between the content size and the amount of details you are putting. Don’t include code, screen shots with commands etc. which do not add value to the concept you are presenting.

8. You can submit a new version of a paper which you already submitted in different forums, (only) when you think that the new version you are submitting has enough context change or a new ideas/opinions are added in. The same version of already submitted papers doesn’t qualify to this contest.

Finally, it is about building your skills to write down your technical idea/concept/understanding in an easy & meaningful way.

HTML Parsing

2009-10-27T15:55:00.007+05:30

Requirement:

* We have to restrict the image width to "430px"; and
* accordingly reduce the height of the image to maintain the aspect (height to
* width) ratio. Take the existing height and width parameters from source,
* determine the ratio, then make width as 430 and calculate the height. You
* need to do this for all images embedded in article if the image width is
* greater than 430px

Possible Design:
1) Read the HTML in memory as string
2) Use HTML Parser to parse the string and fetch the width attribute.
3) Calculate the ration and update it
4) Write the HTML back

Reference:htmlparser.sourceforge.net

-----
Code
-----

package test;

import org.htmlparser.Node;
import org.htmlparser.Parser;
import org.htmlparser.nodes.TagNode;
import org.htmlparser.tags.ImageTag;
import org.htmlparser.util.NodeList;
import org.htmlparser.util.ParserException;

/**
* This class address the following requirement. It uses the HTML parser to get
* the image width and updates it and writes it back.
* 
* Oversized images: We have to restrict the image width to "430px"; and
* accordingly reduce the height of the image to maintain the aspect (height to
* width) ratio. Take the existing height and width parameters from source,
* determine the ratio, then make width as 430 and calculate the height. You
* need to do this for all images embedded in article if the image width is
* greater than 430px (FYI: Article template width is 440px)
* 
* @author Neeraj Singh
* 
*/
public class TransformArticleOversizedImages {

public static final String SOURCE_HTML_FILE_PATH = "C:/01-20-2009-introducing-your-2009-2010-chiefs-cheerleader-2624.dcr";

static void processMyNodes(Node node) {
if (node instanceof TagNode) {
// downcast to TagNode
TagNode tag = (TagNode) node;
// do whatever processing you want with the tag itself
if (tag instanceof ImageTag) {
String width = tag.getAttribute("width");
String height = tag.getAttribute("height");

if (Integer.parseInt(width) > 430) {
tag.setAttribute("width", "430");
tag.setAttribute("height", getHeight(width, height));
}

}
// process recursively (nodes within nodes) via getChildren()
NodeList nl = tag.getChildren();
if (null != nl)
for (int indx = 0; indx < nl.size(); indx++) {
     processMyNodes(nl.elementAt(indx));
    }
  }
 }

 /**
  * Take the existing height and width parameters from source, determine the
  * ratio, then make width as 430 and calculate the height.
  * 
  * @param width
  * @param height
  * @return
  */
 private static String getHeight(String width, String height) {
  double ratio = Double.parseDouble(height) / Double.parseDouble(width);
  double newHeight = 430 * ratio;
  return Integer.toString((int) newHeight);
 }

 public static void main(String[] args) throws ParserException {
  Parser parser = new Parser(SOURCE_HTML_FILE_PATH);

  NodeList nl = parser.parse(null); // passing null to get read complete
  // HTML
  if (nl.size() > 0) {

    for (int i = 0; i < nl.size(); i++) {
      Node node = nl.elementAt(i);
      processMyNodes(node);
    }
  }

  System.out.println(nl.toHtml()); // output the modified HTML
  }
}

Generics and array don't mix : prefer generics

2009-10-24T09:45:00.000+05:30

Effective Java is a very good book on Java written by Joshua Bloch

During one of the study group session, we discussed Item # 25 and concluded that Generics and Array Don't mix and we should prefer Generics.

If you are reading that and want to understand it more, refer A blog entry 'Understanding Java Generics through Erasure' It explains using one example.

Effective Java presentation by the author Joshua Bloch

2009-10-24T09:32:00.000+05:30

We are running "Effective Java" book study group. Came across the following presentation given by the author of the book and is really interesting.

Effective Java Joshua Bloch

Create survey or questionnaire using Google docs forms

2009-10-01T12:33:00.002+05:30

If you are thinking of creating some sort of questionnaire, try using Google Docs. There is a very good feature available for free if you have a google account.

What you need to do, just go to Google Docs, Create new form and you are on...

Below is one sample questionnaire created...

Click the link to participate in survey

XML Techecnology - validation using XML Schema

2009-09-28T10:38:00.000+05:30

Session04 XML Validation Schema

XML Techecnology - Validations using DTD (Document Type Definition)

2009-09-28T10:37:00.001+05:30

Session03 XML Validation DTD