====== Vererbung ======

===== Einführungsbeispiel: Particle engine =====
<code java>
World w = new World(800, 600);

while(true) {
   new Particle(Math.random() * 20 - 10, 
   Math.random() *(-20) - 10,
   Math.random() * 20 - 10);
}


class Particle extends Rectangle {

   double vx;
   double vy;
   double vw;

   public Particle(double vx1, double vy1, double vw1) {
      super(380, 550, 40, 40);
      vx = vx1;
      vy = vy1;
      vw = vw1;
      setBorderColor(null);
      setFillColor(
      Math.floor(Math.random() * 255 * 255 * 255));
      setAlpha(Math.random());
   }

   public void act() {
      move(vx, vy);
      rotate(vw);
      vy = vy + 0.5;
      if(isOutsideView()) {
         destroy();
      }
   }
   

}
</code>