tictactoe.java

此源码为机械工业出版社出版的《Java语言程序设计》第三版所配套的书中所有源代码。

// TicTacToe.java: Play the TicTacToe game
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.LineBorder;

public class TicTacToe extends JApplet
{
  // Indicate which player has a turn, initially it is the X player
  private char whoseTurn = 'X';

  // Create and initialize cells
  private Cell[][] cell =  new Cell[3][3];

  // Create and initialize a status label
  private JLabel jlblStatus = new JLabel("X's turn to play");

  // Initialize UI
  public void init()
  {
    // Panel p to hold cells
    JPanel p = new JPanel();
    p.setLayout(new GridLayout(3, 3, 0, 0));
    for (int i=0; i<3; i++)
      for (int j=0; j<3; j++)
        p.add(cell[i][j] = new Cell());

    // Set line borders on the cells panel and the status label
    p.setBorder(new LineBorder(Color.red, 1));
    jlblStatus.setBorder(new LineBorder(Color.yellow, 1));

    // Place the panel and the label to the applet
    this.getContentPane().add(p, BorderLayout.CENTER);
    this.getContentPane().add(jlblStatus, BorderLayout.SOUTH);
  }

  // This main method enables the applet to run as an application
  public static void main(String[] args)
  {
    // Create a frame
    JFrame frame = new JFrame("Tic Tac Toe");

    // Create an instance of the applet
    TicTacToe applet = new TicTacToe();

    // Add the applet instance to the frame
    frame.getContentPane().add(applet, BorderLayout.CENTER);

    // Invoke init() and start()
    applet.init();
    applet.start();

    // Display the frame
    frame.setSize(300, 300);
    // frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
  }

  // Determine if the cells are all occupied
  public boolean isFull()
  {
    for (int i=0; i<3; i++)
      for (int j=0; j<3; j++)
        if (cell[i][j].getToken() == ' ')
          return false;

    return true;
  }

  // Determine if the player with the specified token wins
  public boolean isWon(char token)
  {
    for (int i=0; i<3; i++)
      if ((cell[i][0].getToken() == token)
          && (cell[i][1].getToken() == token)
          && (cell[i][2].getToken() == token))
      {
        return true;
      }

    for (int j=0; j<3; j++)
      if ((cell[0][j].getToken() ==  token)
          && (cell[1][j].getToken() == token)
          && (cell[2][j].getToken() == token))
      {
        return true;
      }

    if ((cell[0][0].getToken() == token)
        && (cell[1][1].getToken() == token)
        && (cell[2][2].getToken() == token))
    {
      return true;
    }

    if ((cell[0][2].getToken() == token)
        && (cell[1][1].getToken() == token)
        && (cell[2][0].getToken() == token))
    {
      return true;
    }

    return false;
  }

  // An inner class for a cell
  public class Cell extends JPanel implements MouseListener
  {
    // Token used for this cell
    private char token = ' ';

    public Cell()
    {
      setBorder(new LineBorder(Color.black, 1)); // Set cell's border
      addMouseListener(this);  // Register listener
    }

    // The getter method for token
    public char getToken()
    {
      return token;
    }

    // The setter method for token
    public void setToken(char c)
    {
      token = c;
      repaint();
    }

    // Paint the cell
    public void paintComponent(Graphics g)
    {
      super.paintComponent(g);

      if (token == 'X')
      {
        g.drawLine(10, 10, getSize().width-10, getSize().height-10);
        g.drawLine(getSize().width-10, 10, 10, getSize().height-10);
      }
      else if (token == 'O')
      {
        g.drawOval(10, 10, getSize().width-20, getSize().height-20);
      }
    }

    // Handle mouse click on a cell
    public void mouseClicked(MouseEvent e)
    {
      if (token == ' ') // If cell is not occupied
      {
        if (whoseTurn == 'X')  // If it is the X player's turn
        {
          setToken('X');  // Set token in the cell
          whoseTurn = 'O';  // Change the turn
          jlblStatus.setText("O's turn");  // Display status
          if (isWon('X'))
            jlblStatus.setText("X won! The game is over");
          else if (isFull())
            jlblStatus.setText("Draw! The game is over");
        }
        else if (whoseTurn == 'O') // If it is the O player's turn
        {
          setToken('O'); // Set token in the cell
          whoseTurn = 'X';  // Change the turn
          jlblStatus.setText("X's turn"); // Display status
          if (isWon('O'))
            jlblStatus.setText("O won! The game is over");
          else if (isFull())
            jlblStatus.setText("Draw! The game is over");
        }
      }
    }

    public void mousePressed(MouseEvent e)
    {
      // TODO: implement this java.awt.event.MouseListener method;
    }

    public void mouseReleased(MouseEvent e)
    {
      // TODO: implement this java.awt.event.MouseListener method;
    }

    public void mouseEntered(MouseEvent e)
    {
      // TODO: implement this java.awt.event.MouseListener method;
    }

    public void mouseExited(MouseEvent e)
    {
      // TODO: implement this java.awt.event.MouseListener method;
    }
  }
}