这是一个鼠标左键画圆右键画方的程序 请问为什么窗口可以出来但是不能画图

import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

import javax.swing.*;
public class Dome {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    JFrame frame1 = new JFrame();
    Mypanel panel1 = new Mypanel();
    frame1.setBounds(50, 50, 500, 500);
    frame1.addMouseListener(new MyMouseListener());
    frame1.add(panel1);
    frame1.setVisible(true);
    

}

}
class Mypanel extends Panel{
int judge = 0;
int x = 0;
int y = 0;
protected void paintComponent (Graphics g) {
if (judge==1) {
g.setColor(Color.GREEN);
g.fillOval(x, y, 50, 50);
}
if (judge==3) {
g.setColor(Color.RED);
g.fillRect(x, y, 50, 50);
}
}
}

class MyMouseListener implements MouseListener{

@Override
public void mouseClicked(MouseEvent e) {
    // TODO Auto-generated method stub
    final Mypanel a = (Mypanel) e.getSource();
    a.judge = e.getButton();
    a.x = e.getPoint().x;
    a.y = e.getPoint().y;
}

@Override
public void mousePressed(MouseEvent e) {
    // TODO Auto-generated method stub
    
}

@Override
public void mouseReleased(MouseEvent e) {
    // TODO Auto-generated method stub
    
}

@Override
public void mouseEntered(MouseEvent e) {
    // TODO Auto-generated method stub
    
}

@Override
public void mouseExited(MouseEvent e) {
    // TODO Auto-generated method stub
    
}

}
这是一个鼠标左键画圆右键画方的程序
请问为什么窗口可以出来但是不能画图

你这个只实现了点击事件，如果想要画图，不应该是按住左键不松手吗，那不是要实现按压事件吗