请高手们帮帮忙,"玩"一个大家来找茬的游戏!多谢了

请高手们帮帮忙,"玩"一个大家来找茬的游戏!急!谢谢了!
import   java.awt.*;
import   java.awt.event.*;
import   javax.swing.*;

class   test   extends   JFrame
{
JFrame   frm;
JButton   but1,but2,but3;
JPanel   panel,p,pan[];
static   int   j=0;
Container   con;

public   test()
{
JFrame.setDefaultLookAndFeelDecorated(true);
frm=new   JFrame();
con=frm.getContentPane();

//放置按钮
panel=new   JPanel();
but1=new   JButton( "三角形 ");
but2=new   JButton( "矩形 ");
but3=new   JButton( "椭圆形 ");
button   bt=new   button();
but1.addActionListener(bt);
but2.addActionListener(bt);
but3.addActionListener(bt);
panel.add(but1);
panel.add(but2);
panel.add(but3);
con.add(panel,BorderLayout.NORTH);

//放置窗口下方的面板
p=new   JPanel();
p.setLayout(new   GridLayout(3,3,1,1));
//在窗口下方的面板上放置9个小面板
pan=new   JPanel[9];
for(int   i=0;i <9;i++)
{
pan[i]=new   JPanel();
pan[i].setLayout(new   GridLayout(1,1));
p.add(pan[i]);
}
con.add(p,BorderLayout.CENTER);

frm.setTitle( "绘制图形 ");
frm.setSize(500,400);
frm.setVisible(true);
frm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frm.setResizable(false);
frm.show();
}

class   button   implements   ActionListener
{
public   void   actionPerformed(ActionEvent   e)
{
if(j <9){
if(e.getSource()==but1)
{
pan[j].add(new   Triangle());
frm.validate();     //刷新窗口，否则图形无法显示
}
else   if(e.getSource()==but2)
{
pan[j].add(new   rect());
frm.validate();
}
else   if   (but3==e.getSource())
{
pan[j].add(new   Ellipse());
frm.validate();
}
j++;
}
}
}


public   static   void   main(String   age[])
{
new   test();
}
}
//三个图形类定义在外部
class   Triangle   extends   JPanel
{
protected   void   paintComponent(Graphics   g)
{
super.paintComponent(g);
g.setColor(Color.cyan);
int   a=this.getSize().width;
int   b=this.getSize().height;
int   xpoints[]={a/2,0,a};
int   ypoints[]={0,b,b};
g.fillPolygon(xpoints,ypoints,3);

}
}


class   rect   extends   JPanel
{
protected   void   paintComponent(Graphics   g)
{
super.paintComponent(g);
g.setColor(Color.red);
// a=pan[j].getSize().width;
// b=pan[j].getSize().height;
// g.fillRect(a-10,b-10,a-60,a-30);
g.fillRect(0,0,this.getSize().width,this.getSize().height);
}
}

class   Ellipse   extends   JPanel
{
protected   void   paintComponent(Graphics   g)
{
super.paintComponent(g);
g.setColor(Color.blue);
g.fillOval(0,0,this.getSize().width,this.getSize().height);
}
}


________________________________________
import   java.awt.*;
import   java.awt.event.*;
import   javax.swing.*;

class   test   extends   JFrame
{
JFrame   frm;
JButton   but1,but2,but3;
JPanel   panel,p,pan[];