Java动画旋转和移动对象

Question

我的Java程序有点问题。我想要显示一个滚动圆圈的动画，并且该圆圈在边缘上有一根棍子，而这个圆圈上的小圆圈正从endOfTheStick移动到contactPoint并再次返回。问题在于移动这个较小的圆圈。

这些功能为我画了一个旋转的圆圈，圆圈边缘的一根棍子和棍子末端的一个小圆圈：

    private void doDrawing(Graphics g) {
        Graphics2D g2d = (Graphics2D) g.create();

        // Drawing slippery slope
        g2d.drawPolygon(polyX, polyY, 3);

        // Set start position
        g2d.translate(50-r1/2, startY-r1);
        g2d.rotate(polyAngle, r1/2, r1);

        /* Drawing circle
            x-value of shift
        */
        g2d.translate(x, 0);
        g2d.rotate(rotateAngle, r1/2, r1/2);
        g2d.drawOval(0, 0, r1, r1);
        g2d.drawLine(0, r1/2, r1, r1/2);
        g2d.drawLine(r1/2, 0, r1/2, r1);

        //Rotating stick
        AffineTransform.getRotateInstance(speedStickAngle, stickContact[0], stickContact[1]).transform(stickEnd, 0, stickEnd, 0, 1);
        g2d.drawLine(stickContact[0], stickContact[1], (int)stickEnd[0], (int)stickEnd[1]);

        //Rotating and moving small circle
        AffineTransform.getRotateInstance(speedStickAngle, stickContact[0], stickContact[1]).transform(centerOfSmallCircle, 0, centerOfSmallCircle, 0, 1);
        g2d.drawOval((int)centerOfSmallCircle[0]-r2/2, (int)centerOfSmallCircle[1]-r2/2, r2, r2);
    }

    @Override
    public void paintComponent(Graphics g) {

        super.paintComponent(g);
        doDrawing(g);
        tm.start();
    }

    public void actionPerformed(ActionEvent e){
        if(x<0||x>(getWidth())){
            xSpeed =- xSpeed;
            speedAngle =- speedAngle;
            speedStickAngle =- speedStickAngle;
        }
        x = x + xSpeed;
        rotateAngle = rotateAngle + speedAngle;
        repaint();
    }
}