Interface in Java

interface Inter

{

    final int n=3;

    void multiplication(); 

    void addition();

     void  square();

    void cube();

}

class  A

{

   int m;

     A()

       {  m=6;

       }

 }

class B extends A implements Inter

{

public void  multiplication()

{

System.out.println("Multiplication of " + m + " and  " + n + " is " +m*n);

}

public void addition()

{

System.out.println("Addition of " + m + " and " + n + " is " + m+n);

}

public void square()

{

System.out.println("Square of " + m + " is " +m*m);

}

public void cube()

{

System.out.println("Cube of  "+ n + " is " + n*n*n);

}

}

class InterfaceDemo

{

public static void main(String args[])

{

B  b=new B();

b.multiplication();

b.addition();

b.square();

b.cube();

}

}