java - JPanel 转换，我的代码有什么问题？

Question

我是java新手，每天都在学习新东西。今天我偶然发现了一个我无法修复的错误。所以我有一个内部有 JPanel 的 JFrame，现在我想在单击“开始游戏 JLabel”时删除 Jpanel，并使其转换到我的游戏 JPanel(现在我使用测试 JPanel)

JFrame 类:

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class MainMenu extends JFrame {

JPanel panel;
JFrame frame;
JButton playlabel;

 public void mainmenu()   {

    frame = new JFrame();
    panel = new JPanel();
    playlabel = new JButton ("Nieuw Spel");

//frame
    frame.setSize(new Dimension(800, 600));
    frame.getContentPane().setBackground(new Color(14,36,69));
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setMinimumSize(frame.getMinimumSize());  
    frame.setVisible(true);

//panel        
    Dimension expectedDimension = new Dimension(690, 540);
    panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
    panel.setPreferredSize(expectedDimension);
    panel.setMaximumSize(expectedDimension);
    panel.setMinimumSize(expectedDimension);
    panel.setBackground(new Color(14, 36, 69)); 
    panel.add(playlabel);
    playlabel.setAlignmentX(JComponent.CENTER_ALIGNMENT);

//playlabel        
    playlabel.setFont(new Font("Old English Text MT", Font.BOLD, 40));
    playlabel.setBounds(250, 350, 50, 20);
    playlabel.setForeground(new Color(217,144,39));
    playlabel.setBackground(new Color(14,36,69));
    playlabel.setBorderPainted(false);
    playlabel.setFocusPainted(false);
    playlabel.addActionListener(new PlayListener());
}
private class PlayListener extends JFrame implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            JPanel panelgame = Game.Game();
            this.remove(panel);
            this.add(panelgame);
            this.revalidate();
        }
    }
}

游戏类:

package labyrinthproject.View;
import java.awt.Color;
import javax.swing.JPanel;

public class Game {
public static JPanel Game(){
    JPanel panel = new JPanel();
    panel.setSize(690, 540);
    panel.setBackground(new Color(255,36,69));
    return panel;
   }
}

如果有人可以向我解释为什么这不起作用，我将不胜感激!非常感谢!

真诚的，一名 Java 初学者。

Answer 1

您的代码中有很多问题

• 在事件分派(dispatch)线程上创建 GUI
• 不要扩展 JFrame(那里有三(三!)个 JFrame!)
• 遵循命名约定
• 不要过度使用静态方法
• 仅存储您真正需要代表类状态的实例变量
• 请勿使用手动 setSize 或 setBounds 调用。使用 LayoutManager 代替
• 对 frame.setVisible(true) 的调用应该是框架完全组装后的最后调用
• 考虑使用 CardLayout 在面板之间切换 ( http://docs.oracle.com/javase/tutorial/uiswing/layout/card.html )

稍微清理了一下，但确切的结构取决于您最终想要实现的目标:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class MainMenu extends JPanel
{
    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            @Override
            public void run()
            {
                createAndShowGUI();
            }
        });
    }

    private static void createAndShowGUI()
    {
        JFrame mainFrame = new JFrame();
        mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel mainMenu = new MainMenu();
        mainFrame.getContentPane().add(mainMenu);

        mainFrame.pack();
        mainFrame.setLocationRelativeTo(null);
        mainFrame.setVisible(true);
    }

    MainMenu()
    {
        setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));

        Dimension expectedDimension = new Dimension(690, 540);
        setPreferredSize(expectedDimension);
        setBackground(new Color(14, 36, 69));

        JButton newGameButton = new JButton ("Nieuw Spel");
        newGameButton.setAlignmentX(JComponent.CENTER_ALIGNMENT);
        newGameButton.setFont(new Font("Old English Text MT", Font.BOLD, 40));
        newGameButton.setForeground(new Color(217,144,39));
        newGameButton.setBackground(new Color(14,36,69));
        newGameButton.setBorderPainted(false);
        newGameButton.setFocusPainted(false);
        newGameButton.addActionListener(new PlayListener());
        add(newGameButton);
    }

    private class PlayListener implements ActionListener 
    {
        @Override
        public void actionPerformed(ActionEvent e) 
        {
            removeAll();
            GamePanel gamePanel = new GamePanel();
            add(gamePanel);
            revalidate();
        }
    }
}

class GamePanel extends JPanel
{
    GamePanel()
    {
        setBackground(new Color(255,36,69));
    }
}