Liu's homework

HelloWorld.java

abstract interface iVolume
{
   public void showData();
   public double vol();
}

abstract class CSphere implements iVolume
{
   final double PI = 3.14;
   protected int x;
   protected int y;
   protected int r;

   public double vol() {
        double volume = 4.0/3 * this.PI* Math.pow(this.r, 3);
     return volume;
   }

   public void showData() {
     System.out.println("center: (" + this.x + ", " + this.y + ')');
     System.out.println("radius: " + this.r);
     System.out.println("volume: " + vol());
   }
}

class CCircle extends CSphere
{
 public CCircle(int x, int y , int r) {
   this.x = x;
   this.y = y;
   this.r = r;
 }

}

public class HelloWorld
{
 public  static void main( String args[])
 {
   CCircle cir= new CCircle(8,6,2);
   cir.showData();
 }
}