Can anybody give me information about how to test the Java based application? The information I need is about how should be the approach, what all I need to cover while testing these type of applications etc.
From a functional standpoint, it doesn't matter what language/platform the application uses, so being a Java application or not really doesn't matter. Your general approach should be the same as for any other application. However, there are some implications and special things to test depending on what is being used.
now.. what exactly do you mean by "Java based application"? J2EE or servlets/jsp (server side java with web clients)? Browser based Java Applets? Java (Swing/SWT/AWT) desktop application? JNLP/Webstart?
The best approach in this situation is testing in two levels:
1) have unit test (e.g. in JUnit) that test server side, better created by developers. They should cover code (use code coverage tools if you want percentage)
2) have system test cases for command line - here you should not care about language just as Corey said. Cover requirements, use cases or whatever input you have.