小编ios*_*007的帖子

我正在使用JButton的Action侦听器来绘制不同的形状.它工作正常,但如何在面板上保留以前绘制的形状？因为按下之前形状的另一个按钮已经消失.

jButton1.setText("Button1");
    jButton1.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jButton1ActionPerformed(evt);
        }
    });

jButton2.setText("Button2");
    jButton2.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jButton2ActionPerformed(evt);
        }
    });


private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
    // TODO add your handling code here:
    s = evt.getActionCommand();
    repaint();

}
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
    s = evt.getActionCommand();
    repaint();

}

.......和paintComponent方法是

 protected void paintComponent(Graphics g) {
        super.paintComponent(g);


        System.out.println("====>>> " + s);
        switch (s) {

            case "Button1":
                g.drawRoundRect(20,20,40,40,100,200);
                break;

            case "Button2":
                g.drawRect(0, 0, 200, 200);
                break;

            default:
                g.drawOval(40, 40, …