作业2之有界面的四则运算（没写好晚上在该）

import java.awt.*; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.util.Random; 
import javax.swing.*; 
class MyPanel extends Panel implements ActionListener{     
    JButton button; 
    JTextField text1, text2, text3; 
    JLabel label1, label2; 
    public int resultNum; 
     
    MyPanel() 
    { 
        button = new JButton("获取题目"); 
        button.addActionListener(this); 
        text1 = new JTextField(5); 
        text1.setEditable(false); 
        text2 = new JTextField(5); 
        text2.setEditable(false); 
        text3 = new JTextField(5); 
        label1 = new JLabel("+"); 
        label2 = new JLabel("="); 
     
        this.add(button); 
        this.add(text1); 
        this.add(label1); 
        this.add(text2); 
        this.add(label2); 
        this.add(text3); 
    } 
 
    public void actionPerformed(ActionEvent e) { 
        Random random = new Random(); 
        int num1 = random.nextInt(100); 
        int num2 = random.nextInt(100); 
        resultNum = 0; 
        int sizeof = random.nextInt(4); 
        String str = ""; 
        
        switch(sizeof) 
        { 
        case 0: 
            str = "+"; 
            resultNum  = num1 + num2; 
            break; 
       case 1: 
            str = "-"; 
            resultNum = num1 - num2; 
            break; 
        case 2: 
            str = "*"; 
            resultNum = num1 * num2; 
            break; 
        case 3: 
            str = "/"; 
            resultNum = num1 / num2; 
            break; 
        } 
        label1.setText(str); 
        text1.setText(Integer.toString(num1)); 
        text2.setText(Integer.toString(num2)); 
    } 
} 
 public class ComputerFrame extends JFrame implements ActionListener{ 
     MyPanel panel; 
     JButton button1; 
     JLabel label3; 
     
     ComputerFrame() 
     { 
         this.setTitle("随机计算器"); 
         setLayout(new FlowLayout()); 
         panel = new MyPanel(); 
         button1 = new JButton("确认答案"); 
         button1.addActionListener(this); 
         label3 = new JLabel(); 
         this.add(panel); 
         this.add(button1); 
         this.add(label3);    
         setVisible(true); 
         setExtendedState(Frame.MAXIMIZED_VERT); 
         setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
         setBounds(450, 300, 380, 125); 
         validate(); 
    } 
  
     public void actionPerformed(ActionEvent e) { 
 
         if (panel.text3.getText().length() == 0) { 
             label3.setText("你还没有回答呢"); 
         } 
     else  
         { 
             int result = Integer.parseInt(panel.text3.getText()); 
              
             if (result != panel.resultNum)  
             { 
                label3.setText("你回答错误"); 
             }  
             else 
             { 
                 label3.setText("你回答正确"); 
             } 
         } 
     } 
 }

}