Java第六次作业

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

public class GoodLucky extends JFrame implements ActionListener{
 
 JTextField tf = new JTextField();
 JButton b1 = new JButton("开始");
 JButton b2 = new JButton("停止");
 boolean isGo = false;
 public GoodLucky(){
  b1.setActionCommand("start");  
  JPanel p = new JPanel();
  p.add(b1);
  p.add(b2);
    
  b1.addActionListener(this);
  b2.addActionListener(this);
  b2.setEnabled(false);
  
  this.getContentPane().add(tf,"North");
  this.getContentPane().add(p,"South");
  this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  this.setSize(300,200);
  this.setLocation(300,300);
  Cursor cu = new Cursor(Cursor.HAND_CURSOR);
  this.setCursor(cu);
  this.setVisible(true);
  tf.setText("welcome you!                  ");
  this.go();
  
 }
 
 public void go(){
  while(true){
   if(isGo == true){
    String s = "";
    for(int j = 1; j <= 7;j++){
     int i = (int)(Math.random() * 33) + 1;
     if(i < 10){
      s = s + "  0" + i;
     }else{
      s = s + "  " + i;
     }
     
    }
    tf.setText(s);
   }
   
   try{
    Thread.sleep(10);
   }catch(java.lang.InterruptedException e){
    e.printStackTrace();
   }
   
  }
  
 } 
 
  
 public void actionPerformed(ActionEvent e){
  String s = e.getActionCommand();
  if(s.equals("start")){
   isGo = true;
   b1.setEnabled(false);
   b2.setEnabled(true);
  }else{
   isGo = false;
   b2.setEnabled(false);
   b1.setEnabled(true);
  }
  
 }
 
  
 public static void main(String[] args){
  new GoodLucky();  
 }
}