Question: Is there any way to debug only specific code or method of one of the class in an application without executing entire code from main method.
One way would be writing junit for that class and debugging it with break point.Is there any there way?

Answer: 
You can have multiple main methods in your project - one in every class. If you wan't to debug some code in a specific class only, you can add a main method to that class and execute only the desired code. For launching your program, you can use your "main main method" again.

Note: in fact this is kind of similar to a JUnit test, except that you control everything and are not bound to the JUnit structure/syntax/etc.

Note 2: maybe you need to do some setup like in JUnit, too, if your class to be debugged relies on other parts of the project.
There is no way to debug your class without entrypoint (junit also have entrypoint). Java entrypoint is method Main.