java - JFrame 重绘/重载

Question

我在开始新 session 时遇到困难。当我使用菜单选项新游戏时，我得到一个新实例——实际上，我只想用一个新实例替换当前实例。我已经尝试了很多不同的东西，但仍然无法解决......

这是我的代码:

package tictactoe;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class TicTacToe2 extends JFrame implements ActionListener {

char[][] game = new char[3][3];
JButton[][] buttons = new JButton[3][3]; 

JButton menuItem      = new JButton();   
JMenu     menu        = new JMenu  ("TicTacToe");
JMenuItem newgame     = new JMenuItem("Start New Game"), 
          exit        = new JMenuItem("Exit"); 

TicTacToe2()
{
    super("Tic Tac Toe");
    setSize(500, 600);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setVisible(true);
    setLayout( new BorderLayout());

    JPanel northPanel= new JPanel();
    northPanel.setLayout(new FlowLayout(FlowLayout.LEFT));  
    add("North", northPanel);

    JPanel buttonPanel = new JPanel();
    buttonPanel.setLayout(new GridLayout(3,3, 4, 4));
    add("Center", buttonPanel);
    Font font = new Font("Serif", Font.BOLD, 32);

    for (int row=0; row < game.length; row++)
    {
        for (int col =0; col < game[row].length; col++)
        {
            game[row][col] = ' ';
            JButton b = new JButton(" ");
            b.setFont(font);
            b.setBackground(Color.green);
            b.addActionListener(this);
            buttons[row][col] = b;
            buttonPanel.add(b);
        }
    } 

    menu.add(newgame);  
    menu.add(exit);
    newgame.addActionListener(this); 
    exit.addActionListener(this); 

    JMenuBar bar = new JMenuBar( ); 
    bar.add(menu);  
    setJMenuBar(bar); 

} 
public void actionPerformed(ActionEvent e) {
    Object  menusource = e.getSource();   
    if(menusource ==  newgame){ 
        new TicTacToe2();   
    }else if(menusource ==  exit){
        System.exit(0);
    }  
} 
public static void main(String[] args) {
    TicTacToe2 ttt = new TicTacToe2();

}
}

Answer 1

每次通过“新游戏”菜单时，您都在创建一个新实例:

        new TicTacToe2();   

如果您只想重置实例，请编写一个将游戏状态设置为初始状态的 reset() 方法。