这个是我作业的部分代码,完整的代码在上传的文件里.
  代码的目的是:当调用public TimePanel()
    {
        start();
    }
是,在panel上显示系统的时间.
   我执行的结果没任何显示不知道为什么.....请大侠指点!
paintPerformedpublic class TimePanel extends JPanel 
{
    public TimePanel()
    {
        start();
    }
    
    public void paintPerformed(Graphics g)
    {
        super.paintComponent(g);
        Graphics2D g2=(Graphics2D)g;
        
        //to show the present time
        Date date=new Date();
        DateFormat dateFormat = DateFormat.getTimeInstance();
        String d = dateFormat.format(date);
        g2.drawString(d,100, 200);
        if(beep==true)
        {
            Toolkit.getDefaultToolkit().beep();
        }
        
    }
    
    
    
    public void setBeep()
    {
        this.beep=true;
    }
    
    public void  makeButton()
    {
        //create button
        JButton startButton=new JButton("start");
        JButton stopButton=new JButton("stop");
        JButton beepButton=new JButton("beep");
        
        //add button to the panel
        add(startButton);
        add(stopButton);
        add(beepButton);
        
        //action of the button
        startButton.addActionListener(new java.awt.event.ActionListener()
         {
            public void actionPerformed(ActionEvent e)
             {
            
                 start();
               }
             }
         );

        
         stopButton.addActionListener(new java.awt.event.ActionListener()
         {
            public void actionPerformed(ActionEvent e)
             {
                  stop();
              }
         });
         
         beepButton.addActionListener(new java.awt.event.ActionListener()
         {
            public void actionPerformed(ActionEvent e)
             {
             Toolkit.getDefaultToolkit().beep();
             }
         });
         }

    public void start()
    {
       StartAction lis = new StartAction();
       t = new Timer(1000, lis);
       t.start();
    }
    
    public void stop()
    {
        t.stop();
    }

    private boolean beep;
    private Timer t;
    
    //inner class  StartAction
    class StartAction  implements ActionListener
    {
           public void actionPerformed(ActionEvent event)
          {
            [color=FF00FF] repaint();[/color]
            }
     }
    
    public static void main(String[] args) 
    {
        // TODO Auto-generated method stub
    }

}

StartAction为TimePanel的内部类,当调用StartAction的repaint方法时,会调用到TimePanel的paintPerformed方法吗?