private void checkKeys(){
        if("space".equals(Greenfoot.getKey())){
            moveCrane(0);
        }
        if(Greenfoot.isKeyDown("up")){
            moveCrane(1);
        }
        if(Greenfoot.isKeyDown("down")){
            moveCrane(2);
        }
        if(Greenfoot.isKeyDown("left")){
            moveCrane(3);
        }
        if(Greenfoot.isKeyDown("right")){
            moveCrane(4);
        }
    }