Überschrift

public class Circle {

     public double x, y;

     public double r;

     public double circumference() {

         return 2 * Math.PI * r;

     }

     public double area() {

         return Math.PI * r * r;

     }

     public static void main(String[] args) {

     }

}

public class CircleTest {

     public static void main(String[] args) {

         Circle c;

         c = new Circle();

         c.x = 2.0;

         c.y = 2.0;

         c.r = 1.0;

         double a = c.area();

         System.out.println(a);

         System.out.println(c.circumference());

     }

}