der code von Ball lautet:public class Ball extends Actors { int xchange = 3; int ychange = -3; public static int counter = 0; public void act() { setLocation(getX() +xchange, getY() +ychange); if(atWorldSide()) { xchange=-xchange; } if(atWorldTop()) { ychange=-ychange; } if(canSee(Stein.class)) { ychange=-ychange; eat(Stein.class); counter = counter + 1; if(counter >= 15) { Greenfoot.stop(); } public boolean atWorldTop() { if(getY<20) return true; else return false; } } public boolean atWorldSide() { if(getX() < 20 || getX() > getWorld().getWidth()-20) return true; else return false; } public boolean atWorldBottom() { if(getY() > 20 || getY() < getWorld().getHeight()-20) return true; else return false; }