Java 小例子：猜数字游戏

这是一个猜数字的游戏。用户输入 1~1000 以内的任意数字，程序给出它是大了还是小了，直到猜出正确的结果。

Code:

1. import javax.swing.*;  
2. import java.awt.BorderLayout;  
3. import java.awt.event.ActionListener;  
4. import java.awt.event.ActionEvent;  
5. import java.util.Random;  
6.    
7. /** 
8.  * 猜数字 
9.  */  
10. public class GuessNumber extends JFrame {  
11.    
12.     private Random r = new Random();  
13.    
14.     private int result = r.nextInt(1000) + 1;  
15.    
16.     private int counter = 0;  
17.    
18.     private boolean finished = false;  
19.    
20.     private GuessNumber thisFrame = this;  
21.    
22.     private ActionListener guessButtonListener = new ActionListener() {  
23.         public void actionPerformed(ActionEvent e) {  
24.             if (!finished) {  
25.                 String user_guess = textbox.getText();  
26.                 if (user_guess.length() == 0) {  
27.                     messageLabel.setText("输入文本不能为空。");  
28.                 } else {  
29.                     try {  
30.                         int guess = Integer.parseInt(user_guess);  
31.                         counter++;  
32.    
33.                         if (guess < result) {  
34.                             messageLabel.setText("你输入的数字 " + guess + " 比结果小。");  
35.                         } else if (guess > result) {  
36.                             messageLabel.setText("你输入的数字 " + guess + " 比结果大。");  
37.                         } else {  
38.                             finished = true;  
39.                             messageLabel.setText("OK，经过" + counter + "次猜测，你终于猜中了。");  
40.                             button.setText("再来一次");  
41.                         }  
42.                     } catch (NumberFormatException e1) {  
43.                         messageLabel.setText("请输入数字。");  
44.                     }  
45.                 }  
46.             } else {  
47.                 result = r.nextInt(1000) + 1;  
48.                 counter = 0;  
49.                 finished = false;  
50.                 messageLabel.setText("请输入一个 1~1000 之内的数字。");  
51.                 button.setText("猜一猜");  
52.                 thisFrame.setTitle(String.valueOf(result));  
53.             }  
54.         }  
55.     };  
56.    
57.     private JTextField textbox = new JTextField();  
58.    
59.     private JLabel messageLabel = new JLabel("请输入一个 1~1000 之内的数字。");  
60.    
61.     private JButton button = new JButton("猜一猜");  
62.    
63.     public static void main(String[] args) {  
64.         GuessNumber frame = new GuessNumber();  
65.         frame.setVisible(true);  
66.     }  
67.    
68.     public GuessNumber() {  
69.         super("猜数字");  
70.         this.setDefaultCloseOperation(EXIT_ON_CLOSE);  
71.         this.setSize(400, 200);  
72.         this.setLocation(200, 200);  
73.         this.setResizable(false);  
74.    
75.         setupContentPane();  
76.         setupControls();  
77.         this.setTitle(String.valueOf(result));  
78.     }  
79.    
80.     private void setupContentPane() {  
81.         JPanel contentPane = new JPanel(new BorderLayout());  
82.         contentPane.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));  
83.         this.setContentPane(contentPane);  
84.     }  
85.    
86.     private void setupControls() {  
87.         JPanel topPanel = new JPanel(new BorderLayout());  
88.         setupTupPanel(topPanel);  
89.         this.add(topPanel, BorderLayout.NORTH);  
90.         this.add(messageLabel, BorderLayout.CENTER);  
91.     }  
92.    
93.     private void setupTupPanel(JPanel panel) {  
94.         panel.add(textbox, BorderLayout.CENTER);  
95.         button.addActionListener(guessButtonListener);  
96.         panel.add(button, BorderLayout.EAST);  
97.     }  
98. }