A Java source code for Guess Number game (猜數字遊戲)

The Java code below is my implementation of the "guess number game"(猜數字遊戲). It is a fully runnable Java application. A feature of the program is that it supports both Chinese and English languages. You can also copy and configure it on your own.

import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JComboBox;
import javax.swing.DefaultComboBoxModel;
import java.awt.Font;
import java.awt.Color;
import javax.swing.JLabel;
import java.awt.Component;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.Random;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.swing.JTextField;


public class GuessNumber extends JFrame {

 
 private static final long serialVersionUID = 1L;
 private JPanel contentPane;
 private static final Random random = new Random();
 private String randomNumber;
 private int times;
 /**
  * Launch the application.
  */
 public static void main(String[] args) {
  EventQueue.invokeLater(new Runnable() {
   public void run() {
    try {
     GuessNumber frame = new GuessNumber();
     frame.setVisible(true);
    } catch (Exception e) {
     e.printStackTrace();
    }
   }
  });
 }

 private JComboBox comboBox;
 private JLabel label;
 private JButton btnStart;
 private JTextField textField;
 private JButton btnSwitchLanguage;
 private JLabel additionalLabel;
 private JButton btnEnter;
 private JLabel giAgiBJLabel;
 /**
  * Create the frame.
  */
 public GuessNumber() {
  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  setBounds(400, 100, 450, 300);
  setResizable(false);
  setTitle("Guess Number");
  contentPane = new JPanel();
  contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
  contentPane.setLayout(null);
  setContentPane(contentPane);
  
  comboBox = new JComboBox();
  comboBox.setForeground(Color.BLUE);
  comboBox.setFont(new Font("微軟正黑體", Font.BOLD, 16));
  comboBox.setModel(new DefaultComboBoxModel(new String[] {"English", "\u4E2D\u6587"}));
  comboBox.setBounds(150, 125, 150, 35);
  contentPane.add(comboBox);
  
  label = new JLabel();
  setLabel();
  contentPane.add(label);
  
  btnStart = new JButton("Start");
  btnStart.addActionListener(new ActionListener() {
   public void actionPerformed(ActionEvent arg0) {
    start();
   }
  });
  btnStart.setForeground(Color.RED);
  btnStart.setFont(new Font("Century", Font.BOLD, 14));
  btnStart.setBounds(180, 190, 90, 30);
  contentPane.add(btnStart);
  
  textField = new JTextField();
  textField.setFont(new Font("Tahoma", Font.BOLD, 18));
  textField.setBounds(170, 120, 120, 35);
  textField.setVisible(false);
  textField.addKeyListener(enterListener);
  contentPane.add(textField);
  
  btnSwitchLanguage = new JButton("Switch Language");
  btnSwitchLanguage.addActionListener(new ActionListener() {
   public void actionPerformed(ActionEvent arg0) {
    switchLanguage();
   }
  });
  btnSwitchLanguage.setFont(new Font("Sylfaen", Font.PLAIN, 10));
  btnSwitchLanguage.setBounds(328, 239, 110, 23);
  btnSwitchLanguage.setVisible(false);
  contentPane.add(btnSwitchLanguage);
  
  additionalLabel = new JLabel("without duplicate digits");
  additionalLabel.setFont(new Font("Kartika", Font.BOLD, 16));
  additionalLabel.setForeground(new Color(153, 102, 0));
  additionalLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
  additionalLabel.setBounds(130, 65, 300, 35);
  additionalLabel.setVisible(false);
  contentPane.add(additionalLabel);
  
  btnEnter = new JButton("Enter");
  btnEnter.addActionListener(new ActionListener() {
   public void actionPerformed(ActionEvent arg0) {
    enter();
   }
  });
  btnEnter.addKeyListener(enterListener);
  btnEnter.setBackground(new Color(173, 255, 47));
  btnEnter.setFont(new Font("新細明體", Font.BOLD, 12));
  btnEnter.setForeground(Color.BLUE);
  btnEnter.setBounds(310, 125, 69, 23);
  btnEnter.setVisible(false);
  contentPane.add(btnEnter);
  
  giAgiBJLabel = new JLabel("");
  giAgiBJLabel.setForeground(new Color(0, 0, 255));
  giAgiBJLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
  giAgiBJLabel.setFont(new Font("Comic Sans MS", Font.PLAIN, 28));
  giAgiBJLabel.setBounds(190, 170, 130, 30);
  contentPane.add(giAgiBJLabel);
 }
 
 public KeyListener enterListener = new KeyListener() {
  
  @Override
  public void keyTyped(KeyEvent arg0) {}
  
  @Override
  public void keyReleased(KeyEvent arg0) {}
  
  @Override
  public void keyPressed(KeyEvent arg0) {
   int key = arg0.getKeyCode();
   if (key == KeyEvent.VK_ENTER){
    enter();
   }
  }
 };
 
 private void enter(){
  times++;
  boolean hasNoInputError = checkInputError();
  if (hasNoInputError){
   if (textField.getText().equals(randomNumber)){
    if (comboBox.getSelectedIndex() == 1)
     JOptionPane.showMessageDialog(null, "恭喜你答對了。你一共猜了"+times+"次");
    else 
     JOptionPane.showMessageDialog(null, "Congratulations! Your answer is correct. You have guessed " + times + " times.");
    switchLanguage();
   }
   else {
    setGiAGiB();
   }
  }
 }
 
 private void switchLanguage(){
  btnEnter.setVisible(false);
  comboBox.setVisible(true);
  btnStart.setVisible(true);
  textField.setText("");
  textField.setVisible(false);
  setLabel();
  additionalLabel.setVisible(false);
  btnSwitchLanguage.setVisible(false);
  giAgiBJLabel.setVisible(false);
  
 }
 
 private boolean checkInputError(){
  String inputText = textField.getText().trim();
  if (inputText.length()!=4){
   if (comboBox.getSelectedIndex() == 1)
    JOptionPane.showMessageDialog(null, "請輸入四位數正整數");
   else 
    JOptionPane.showMessageDialog(null, "Please enter a 4-digit integer");
   return false;
  }
  Pattern pattern = Pattern.compile("\\d\\d\\d\\d");
  Matcher matcher = pattern.matcher(inputText);
  if (!matcher.find()){
   if (comboBox.getSelectedIndex() == 1)
    JOptionPane.showMessageDialog(null, "請輸入有效的正整數");
   else 
    JOptionPane.showMessageDialog(null, "Please enter a valid integer");
   return false;
  }
  
  for (int i = 0; i <= 2; i ++){
   for (int j = i+1; j <= 3 ; j ++ ){
    if (inputText.charAt(i) == inputText.charAt(j)){
     if (comboBox.getSelectedIndex() == 1)
      JOptionPane.showMessageDialog(null, "輸入有誤。四個數字都不能重複");
     else 
      JOptionPane.showMessageDialog(null, "Input error. There should be no duplicate digits");
     return false;
    }
   }
  }
  textField.setText(inputText);
  return true;
 }
 
 
 private void setLabel(){
  label.setText("Select a language");
  label.setForeground(new Color(153, 102, 0));
  label.setAlignmentX(Component.CENTER_ALIGNMENT);
  label.setFont(new Font("Kartika", Font.BOLD, 16));
  label.setBounds(150, 60, 150, 35);
 }
 
 private void start(){
  setRandomNumber();
  btnEnter.setVisible(true);
  comboBox.setVisible(false);
  btnStart.setVisible(false);
  textField.setVisible(true);
  btnSwitchLanguage.setVisible(true);
  setTexts();
  times = 0;
 }
 
 private void setRandomNumber(){
  boolean[] used = new boolean[10];
  int d1 = random.nextInt(10);
  used[d1] = true;
  int d2 =  random.nextInt(9);
  if (used[d2]) d2++;
  used[d2] = true;
  int d3 = random.nextInt(8);
  if (used[d3]) d3++; 
  if (used[d3]) d3++;
  used[d3] = true;
  int d4 = random.nextInt(7);
  if (used[d4]) d4++; 
  if (used[d4]) d4++;
  if (used[d4]) d4++;
  randomNumber = "" + d4 + d3 + d2 + d1;
  System.out.println(randomNumber);
 }
 
 private void setGiAGiB(){
  int a = 0;
  for (int i = 0 ; i < 4 ; i ++){
   if (textField.getText().charAt(i) == randomNumber.charAt(i))
    a++;
  }
  
  int b = 0;
  for (int i = 0 ; i < 4 ; i ++){
   if (randomNumber.contains(textField.getText().charAt(i) + "")){
    if (textField.getText().charAt(i) != randomNumber.charAt(i))
     b++;
   }
  }
  giAgiBJLabel.setText(a + "A" + b + "B");
  giAgiBJLabel.setVisible(true);
 }
 
 private void setTexts(){
  
  if (comboBox.getSelectedIndex() == 1){
   setTitle("猜數字");
   label.setBounds(80, 40, 300, 35);
   label.setFont(new Font("微軟正黑體", Font.BOLD, 16));
   label.setText("請輸入一個數字不重複的四位數正整數");
   btnSwitchLanguage.setBounds(328, 239, 110, 23);
   btnSwitchLanguage.setFont(new Font("微軟正黑體", Font.PLAIN, 10));
   btnSwitchLanguage.setText("切換語言");
   btnEnter.setText("輸入");
  }
  else {
   setTitle("Guess Number");
   label.setBounds(75, 40, 300, 35);
   label.setText("Please enter a 4-digit positive integer");
   btnSwitchLanguage.setText("Switch Language");
   btnSwitchLanguage.setFont(new Font("Sylfaen", Font.PLAIN, 10));
   btnSwitchLanguage.setBounds(328, 239, 110, 23);
   additionalLabel.setVisible(true);
   btnEnter.setText("Enter");
   
  }
  
  
 }
}