public DoubleBall(int x, int y, double ratio) {
super(x, y);
inner_ = new Ball(x, y);
inner_.setSize((int) (this.size * ratio));
this.paint.setColor(Color.WHITE);
this.ratio = ratio;
}
@Override
public void setSize(int size) {
super.setSize(size);
inner_.setSize((int) (this.size * ratio));
}