Class Declarations and Modifiers
Whne we would like to declare the class and modies it then we use nested or inner class . some rules are there :
> each sourse code file have a one public class only.
> File name and class name should be same .
> packege should be first line in the sourse code if class is a part of package .
>Import and package statements apply to all classes within a source code file.
Modifiers fall into two categories :
> Access modifiers: public, protected, private
> Nonaccess modifiers (including strictfp, final, and abstract.