import java.awt.*;
import java.awt.event.*;

public class MyButton extends Button
{
    private MyButton MB=null;
    public MyButton()
    {
        enableEvents(AWTEvent.MOUSE_MOTION_EVENT_MASK);
    }
    public void setfriend(MyButton MB)
    {
        this.MB=MB;
    }
    protected void processMouseMotionEvent(MouseEvent e)
    {
        setVisible(false);
        MB.setVisible(true);
    }
}

import java.awt.*;
import java.awt.event.*;

public class TestMyButton extends Frame
{
    public static void main(String []args)
    {
        TestMyButton tmb=new TestMyButton();
        MyButton mb1=new MyButton();
        MyButton mb2=new MyButton();
        
        tmb.add(mb1,"North");
        tmb.add(mb2,"South");
        tmb.setSize(400,400);
        tmb.setVisible(true);
        mb1.setfriend(mb2);//谁能给讲解下，此处为什么为死循环；
        mb2.setfriend(mb1);//谁能给讲解下，此处为什么为死循环；
        mb2.setVisible(false);
    }
}