public void move( int distance ){
        switch ( direction ) {
            case UP:
                setLocation( new Point( x , y - distance ) );
                break;
            case DOWN:
                setLocation( new Point( x , y + distance ) );
                break;
            case LEFT:
                setLocation( new Point( x - distance , y ) );
                break;
            case RIGHT:
                setLocation( new Point( x + distance , y ) );
                break;
        }
        if (x < 0 || y < 0) {
            kill();
        }
    }