Java-Success Blog

Are you a Java beginner? Why good Java developers are self-taught?

2014-11-22T00:15:00.000+11:00

Q. Are you a beginner wanting to learn Java? A. If the answer is yes, read on. You can't learn much with a paid 5 to 10 days or even a 3 month course. It will only set you back on your wallet. Formal education like computer science degree is very valuable and will be well recognized. But, there are a group of people like me who want to make a career transition from other degrees like

Java exception handling beginner mistakes and best practices

2014-11-18T10:01:00.000+11:00

a) Sweeping exceptions under the carpet by doing nothing. try{ //... }catch(SQLException sqe){ // do nothing } In few rare scenarios, it is desired to do nothing with an exception, e.g. in a finally block, you try to close database connection, and some exception occurs. In this case, exception can be ignored. try{ }catch(SQLException sqe){ //... }finally{ try{

Unix Interview Questions and Answers for Java developers

2014-11-13T22:44:00.001+11:00

Most commercial Java applications run in a Unix environment. For example, batch jobs. Here are a few Unix questions and answers to test your Unix knowledge. Q. Can you write a Unix function that parses the command-line arguments? For example: process_txns.ksh -env $ENV -backdate 20130125 A. Usually only nine command line arguments can be accessed using

Debugging and working like a pro with a Java application tutorial with eclipse IDE

2014-10-23T14:15:00.000+11:00

Often you get to work on a fully functional Java application that is already in production to fix production issues or to enhance its existing functionality. As a new Java developer in the team, it is not easy to get started and contributing. The approach would be slightly different from working on a brand new project. Here are a few tips that will help you hit the road running as quickly as

Yammer metrics to monitor RESTful web services and report them via its admin web

2014-10-22T12:29:00.002+11:00

This is a Yammer metrics tutorial to monitor RESTful web services. This extends RESTEasy web service tutorial basic and the basic stand-alone Yammer tutorial. Step 1: The pom.xml file needs to have relevant dependencies defined relating to Yammer and Spring Web in addition to the JAX-RS librraies that was covered in the previous tutorial. <!-- Yammer Metrics --

When to use which Java collection or data structure? and why?

2014-10-10T12:46:00.000+11:00

List, Set, Map, and Queue(access the ends FIFO or LIFO) are the basic Java data structure interfaces for which there are different implementations to cater for different usage patterns. Java data structure interview questions are very popular, and pays to know the differences. #1 Array (Employee[]) Vs List (List<Employee>): Array is a fixed length data structure whilst a List is a

How to prepare or train for Java and JEE Job Interviews?

2014-10-01T17:55:00.000+10:00

What are the core concepts? If you just rely only on your experience alone, it can take a long time to get a good handle on the core concepts and the 16 key areas. The best way to fast track your career is to proactively learn and apply them. What are these 16 technical key areas? Language Fundamentals (LF) Specification Fundamentals (SF) Platform Fundamentals (PF) Design

Yammer metrics to monitor RESTful web services with a Servlet filter

2014-10-01T12:26:00.000+10:00

This extends Yammer metrics to monitor RESTful web services and report them via its admin web to demonstrate how a Servlet filter can be added to gather metrics for response codes for 200, 201, 404, etc to get a count. active requests count requests timing. Step 1: Decorate the "HttpServletResponseWrapper" class. HttpServletResponseWrapper is one particular

Monitoring and gathering statistics with JMX based jconsole and Yammer metrics

2014-09-02T00:21:00.001+10:00

This post extends Yammer Metrics with Spring tutorial to demonstrate how the metrics can be monitored for the TradeEngineMain application. Step 1: Run the TradeEngineMain java class created in the Yammer metrics tutorial. Step 2: From the DOS command prompt, type jconsole C:\Users\akumaras>jconsole Step 3: The jconsole window pops up as shown below. Step 4: You

What are the different ways a Java thread gets blocked or suspended? How will you debug Java threading issues?

2014-08-22T12:02:00.000+10:00

1. It has been put to sleep for a set amount of time public void run(){ try{ while(true){ this.sleep(1000); System.out.println("looping while"); } }catch(InterruptedException ie){ ie.printStackTrace(); } } 2. The thread is suspended by call to wait( ), and will become runnable on a notify or notifyAll

What is a volatile variable in Java and when should you use it?

2014-08-08T23:44:00.001+10:00

Java Multi-threading Interview Questions and Answers Beginner Q&A More beginner Q&A Beginner locks Beginner thread communication Beginner thread sequencing Intermediate Q&A Volatile variable Advanced Q&A Printing odd and even numbers Thread pools ExecutorService Atomic operations CountDownLatch and CyclicBarrier Semaphores and mutexes Three of the Java

How to capture user input in Java or interact with user via command line

2014-08-07T16:24:00.001+10:00

#1: Using the System.console( ) . This will not work within eclipse IDE. You can try it on a DOS or Unix command-line. package com.user.input; import java.io.Console; public class Example1 { public static void main(String[] args) { Console console = System.console(); String input = console.readLine("What is your name:"); System.out.println("User input = " + input); } } The

Top 10 causes of performance issues in Java

2014-08-06T10:03:00.001+10:00

Cause #1: The JVM spends more time performing garbage collection due to improper Garbage Collection (GC) configuration. E.g. Young generation being too small. Heap size is too small (use -Xmx). The application footprint is larger than the allocated heap size. Wrong use of libraries. For example, XML based report generation using DOM parser as opposed to StAX for large reports generated

Java and JSON tutorial converting JSON to object and vice versa with Jackson library

2014-08-05T13:47:00.000+10:00

Q. What is JSON and when to favor it over XML? A. JSON (JavaScript Object Notation) is a lightweight, text-based, language-netral like XML, but less verbose than XML data exchange format. JSOJ is used in Web services to exchange data between client and server. Client makes ajax requests to get snippets of data in JSON format from the server via RESTful web service calls. JSON is easy for humans

Java and XSLT tutorial to transform XML documents

2014-08-05T10:33:00.000+10:00

Q. What is XSLT? A. XSLT (Extensible Stylesheet Language Transformations) is a language for transforming XML documents into other XML, HTML, or plain text documents. XSLT is based on functional prgramming ideas, but it is not a full functional programming language as it lacks ability to treat functions as a first class data type. XSLT supports XPath to query parts of XML. The major

Finding your way around the FIX specification

2014-08-04T18:25:00.000+10:00

FIX and Java FIX tutorial in Java with QuickFIX/j simple example QuickFix Java example sending and receiving FIX messages Finding your way around the FIX specification If you are using FIX spec 4.4 then go to https://fixspec.com/FIX44. The tutorials with QuickFIX/J used NewSingleOrder as the request. The message has the fields like Tag number. FIX message for

QuickFix Java example sending and recieving FIX messages

2014-08-04T18:24:00.003+10:00

FIX and Java FIX tutorial in Java with QuickFIX/j simple example QuickFix Java example sending and receiving FIX messages Finding your way around the FIX specification If you like to work on trading applications, you need to know the FIX protocol and a FIX engine like QuickFIX/J. This extends our simple QuickFIX Java example tutorial. This assumes that

Top 8 things you must know about Java 8 to start coding on the job and talking at the job interviews

2014-08-01T18:09:00.003+10:00

Are you ready to get cracking with Java 8 new features? Here are a comprehensive Java 8 features, tutorials, and examples. Drill down into each. #1: Transforming your thinking from OOP to FOP: One needs to get used to the transformation from imperative programming to functional programming. You like it or not, you will be using functional programming in Java 8, and interviewers

Java 8 using the Predicate functional interface

2014-08-01T17:17:00.001+10:00

The java.util.function package in Java 8 has a number of functional interfaces. Let's look at the Predicate<T> interface that is used for filtering objects from a collection. If you are using a Java version pre Java 8 refer Creating sub lists from a list using predicates to filter. Here is the Java 8 example: Step 1: Create a Driver domain class using the builder design pattern. Refer How

Java and XPath tutorial to extract a subset of an XML

2014-08-01T10:09:00.000+10:00

Q. What is XPath? A. XPath is a query language to extract a part of XML document as an SQL is used to extract a part of a database data or a REGEX (i.e. regular expression) is used to extract a part of text. The XPath expressions can return, XPathConstants.STRING XPathConstants.NUMBER XPathConstants.BOOLEAN XPathConstants.NODE XPathConstants.NODESET Here is a very basic example of XPath in

FIX tutorial in Java with QuickFIX/j simple example

2014-07-31T14:22:00.005+10:00

FIX and Java FIX tutorial in Java with QuickFIX/j simple example QuickFix Java example sending and receiving FIX messages Finding your way around the FIX specification If you like to work on trading applications, you need to know the FIX protocol and a FIX engine like QuickFIX/J. Q. What is FIX Protocol? A. FIX stands for Financial Information eXchange, which is an open

Java and XML tutorial with SAX parser - reading only

2014-07-31T10:27:00.001+10:00

Q. What is a SAX Parser and when will you use it? A. SAX (Simple API for XML) is a stream oriented API like StAX, but Unlike StAX, which can read and write, but SAX can only read. Unlike StAX, which can't validate schema, SAX can perform schema validation. SAX works by iterating over the XML and call certain methods on a "handler" object , which listens to events like

Java and XML tutorial with StAX parser - writing cursor based and iterator based

2014-07-30T13:46:00.000+10:00

package com.xml; import java.math.BigDecimal; import org.springframework.core.style.ToStringStyler; public class Employee { private String name; private String type; private int age; private BigDecimal salary; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getType() { return type; } public void setType(String

Why this Java blog? Are you feeling stagnated or finding it hard to get good Java jobs?

2014-07-29T20:02:00.001+10:00

I can think of 8 reasons As a journal of my valuable experience for future reference, which otherwise would be lost as Java/JEE technologies, frameworks, libraries, and tools are very vast. As a motivator to proactively learn, apply, and experience new concepts, frameworks, and tools without feeling stagnated. Just knowing Java alone is never enough in this fiercely competitive market. You need

Java and XML tutorial with StAX parser - reading

2014-07-29T09:58:00.004+10:00

Q. What is a StAX Parser and when will you use it? A. The StAX Java API for XML processing is designed for parsing XML streams, just like the SAX API's, but StAX is a "pull" API whereas SAX is a "push" API. StAX can do both XML reading and writing whereas SAX can only do XML reading. Q. Why use StAX when there is DOM? A. The DOM parsing involves creating in-memory objects