repaint()方法为什么不能调用?

     调用display（）时打印出GamePanel's display! 但不显示GamePanel's PrintComponent，也就是System.out.println("GamePanel's PrintComponent")这条语句没有执行,repaint()方法为什么不能调用方法 printComponent(Graphics g)

 

 

import java.awt.Graphics;
import javax.swing.JPanel;

public class RepaintDemo 
{
    public static void main(String args[])
    {
        GamePanel gamepanel = new GamePanel();
        gamepanel.display();
    }
}

class GamePanel extends JPanel
{
    public void display()
    {
        System.out.println("GamePanel's display!");
        this.repaint();
    }    
    
    protected void printComponent(Graphics g) {
        // TODO Auto-generated method stub
        System.out.println("GamePanel's PrintComponent");    
    }    
}