interface Shape{ int a=4; double PI=3.14; void area(); } class Circle implements Shape{ public void area(){ System.out.println("The area of circle is "+(PI*a*a)); } } class Square implements Shape{ public void area(){ System.out.println("The area of square is "+(a*a)); } } public class Interface { public static void main(String args[]){ Circle c = new Circle(); Square s = new Square(); c.area(); s.area(); } }