关于paintComponent()如何调用的问题!

Question

rectangleButton.addActionListener(new ActionListener(){
       public void actionPerformed(ActionEvent event){ 
            repaint();
            System.out.println(1);
           
           add(new JPanel(){public void paintComponent(Graphics g){  
           super.paintComponents(g);
           Graphics2D g2 = (Graphics2D) g;
           Rectangle2D rect = new Rectangle2D.Double(leftX, topY, width, height);
               g2.draw(rect);       }});代码如上  点了按钮反映只输出1  是表示我的repaint()放错位置了 为什么他不调用paintComponent() 呢  求解

Answer 1

代码太乱！rectangleButton.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent event) {
        repaint();
        System.out.println(1);
        add(new JPanel() {
            public void paintComponent(Graphics g) {
                super.paintComponents(g);
                Graphics2D g2 = (Graphics2D) g;
                Rectangle2D rect = new Rectangle2D.Double(leftX, topY, width, height);
                g2.draw(rect);
            }
        });
    }
});

Answer 2

rectangleButton.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent event) {
        System.out.println(1);
        add(new JPanel() {  //用的什么布局管理器？
            public void paintComponent(Graphics g) {
                super.paintComponents(g);
                Graphics2D g2 = (Graphics2D) g;
                Rectangle2D rect = new Rectangle2D.Double(leftX, topY, width, height);
                g2.draw(rect);
            }
        });
        repaint();  //换个位置试下
    }
});

Answer 3

 
基本代码如下，楼主自己改改
mPanel tmpmPanel=new mPanel();
 rectangleButton.getParent().add(tmpmPanel);rectangleButton.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent event) {
         tmpmPanel.repaint();
    }
});  class mPanel extends JPanel{              public void paintComponent(Graphics g) {
                super.paintComponents(g);
                Graphics2D g2 = (Graphics2D) g;
                Rectangle2D rect = new Rectangle2D.Double(leftX, topY, width, height);
                g2.draw(rect);
         }
 }