@puneetsardana88
Hey, don't get touchy. I meant well to ask that question since it sounds strange why any user of a class would want to avoid a provided method unless they have a very good reason to do that.
Wanting to know how a method is implemented is a totally different matter I think. Maybe I misunderstood what you wanted to do.
If you simply want to know how charAt is implemented, I believe the JDK install comes with the source code for the String class. Mostly you will find the methods that do not require native implementation. Additionally there is the OpenJDK (Open source java) project which will have the entire sources.
Regards,
Alex.