public void actionPerformed(ActionEvent e) {
    	ArrayList b = craft.getBullets();

        for (int i = 0; i < b.size(); i++) {
        	PlayerBullet m = (PlayerBullet) b.get(i);
        	if (m.isVisible()) 
        		m.move();
            else b.remove(i);
        }
        
        for (int i = 0; i < invaders.size(); i++){
        	Invaders inv = (Invaders) invaders.get(i);
        	if (inv.isVisible())
        		inv.move();
        	else invaders.remove(i); 
        	
        }
        craft.move();
        repaint();  
    }