Nested Class and Inner Classes

It is possible to define a class within another class such classes are known as nested classes.  A nested class has access to all of the variables and methods of its outer class.  But the outer class doesn’t access the variables and methods of nested class.  Since the scope of a nested class is bounded by the scope of its enclosing class.

            There are two types of nested classes: static and non-static

A static nested class is a class started with ‘static’ modifier.  Due to the static it must access the members of its enclosing class through an object.  Direct access cannot be possible.

A non-static class is a class as ordinary representation of class.  The most important type of the non-static class is “Inner class”.  The inner class has access to all of the variables and methods of its outer class.  Thus, inner class scope is fully within the scope of its outer class.

Example:

class outer

{

            int out_x=34;

            void test()

            {

            inner in=new inner();

            in.display();

            }

            class inner

            {

            void display()

            {

            System.out.println("value="+out_x);

            }

            }

}

class test

{

            public static void main(String[] args)

            {

            outer y=new outer();

            y.test();

            }

}