CardLayout，来自单独 class 的面板未显示

Question

我正在为一个相当简单的棋盘游戏制作我的第一个 GUI。除了游戏视图，我还需要主菜单和其他一些视图。不幸的是，我的 GUI 在早上看起来比我还难看，因为整个菜单结构都在一个 class 中。我正在使用卡片布局在不同的视图之间切换，所以我想我可以将这些视图分成不同的 classes。可悲的是，这是我运行遇到问题的地方。我得到的只是一片空白 window.

经过四个小时的研究，我还没有解决我的问题，所以我想问问你们，你们知道我的代码有什么问题吗？即使很难，我认为我已经排除了明显的问题（没有使用卡片布局向我的面板添加面板，没有设置布局等）我仍然认为问题一定非常简单。然而，我发现的任何东西都没有帮助。

关于业务，这是我的 "base GUI"

package teekkariloikka.gui;

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


public class TLGui extends JFrame {

    private static final long serialVersionUID = 1L;

    private static final int WIDTH = 1000;
    private static final int HEIGHT = 800;

    private static final String MAINMENU = "mainmenu";
    private static final String GAME = "game";

    private JPanel basePanel;

    private GameViewPanel gameViewPanel;
    private MainMenuPanel mainMenuPanel;

    JFrame frame = new JFrame();

    //Layout
    private CardLayout cardL = new CardLayout();

    public TLGui(){

        //Frame stuff
        frame.setTitle("Teekkariloikka");
        frame.setSize(WIDTH, HEIGHT);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
        frame.setResizable(false);      

        //This is the panel where I add the ohter panels for menu and game
        basePanel = new JPanel();
        basePanel.setLayout(cardL);

        //Creating the panels I want to add. Excuse the confusing naming.
        gameViewPanel = new GameViewPanel(); 
        mainMenuPanel = new MainMenuPanel();

        //Adding the panels to the basePanel
        basePanel.add(mainMenuPanel, MAINMENU);
        basePanel.add(gameViewPanel, GAME);
        cardL.show(basePanel, MAINMENU);        

        //ADDING basePanel to the frame
        frame.add(basePanel);

        //Action listeners for buttons. Take a look at the classes.
        mainMenuPanel.setNewGameButtonListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e){
                cardL.show(basePanel, GAME);
            }
        });

        gameViewPanel.setMainMenuButtonListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e){{
                cardL.show(basePanel, MAINMENU);
            }
        }); 
    }

    public static void main(String[] args){
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run(){
                new TLGui();
            }
        }); 
    }
}

然后是我的 MainMenuPanel class。这是一项正在进行的工作，但至少应该显示按钮。我尽我最大的努力把我用芬兰语（我的母语）写的所有东西都写下来，我真的希望我不会对我的代码视而不见以至于忘记了什么。

package teekkariloikka.gui;

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

public class MainMenuPanel extends JPanel{

    private static final long serialVersionUID = 1L;

    //Buttons
    private JPanel panel;
    private JButton newGameButton;
    private JButton quitButton;

    //Font
    Font menuFont = new Font("Arial", Font.BOLD, 24);
    //Layout
    private GridBagLayout menuLayout = new GridBagLayout();
    private GridBagConstraints c1 = new GridBagConstraints();

    public MainMenuPanel(){

        panel = new JPanel();

        //For testing //TODO remove
        panel.setBackground(Color.BLACK);

        newGameButton = new JButton("New Game");
        quitButton = new JButton("Quit");

        //New Game -button
        newGameButton.setPreferredSize(new Dimension(200, 100));
        newGameButton.setFont(menuFont);

        //Quit-button
        quitButton.setPreferredSize(new Dimension(200, 100));
        quitButton.setFont(menuFont);

        panel.setLayout(menuLayout);
        c1.insets = new Insets(10, 10, 10, 10);
        c1.gridx = 0;
        c1.gridy = 1;
        panel.add(newGameButton, c1);
        c1.gridx = 0;
        c1.gridy = 2;
        panel.add(quitButton, c1);
    }

    //Idea: 
    public void setNewGameButtonListener(ActionListener listener){
        newGameButton.addActionListener(listener);
    }

    public void setQuitButtonListener(ActionListener listener){
        quitButton.addActionListener(listener);
    }
}

和 GameViewPanel class。也在进行中，但与之前的 class 一样，这应该看起来不错。

package teekkariloikka.gui;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;

public class GameViewPanel extends JPanel{

    private static final long serialVersionUID = 1L;

    private JButton lopetaButton;
    private JButton tallennaButton;
    private JButton menuButton;

    BorderLayout bordL = new BorderLayout();    

    public GameViewPanel(){

        JPanel gameViewPanel = new JPanel();

        gameViewPanel.setLayout(bordL);
        gameViewPanel.setBorder(new EmptyBorder(10, 10, 10, 10)); 

        //Creating toolbar
        JToolBar toolbar = new JToolBar();
        toolbar.setFloatable(false);

        gameViewPanel.setLayout(bordL);
        gameViewPanel.setBorder(new EmptyBorder(10, 10, 10, 10)); 
        gameViewPanel.add(toolbar, BorderLayout.PAGE_START);        

        //Buttons
        lopetaButton = new JButton("Lopeta");
        menuButton = new JButton("Päävalikko");
        tallennaButton = new JButton("Tallenna");

        //Adding buttons to game view toolbar
        toolbar.add(lopetaButton); //TODO Add functionality!
        toolbar.add(tallennaButton); //TODO Add functionality!
        toolbar.add(menuButton); //TODO Add functionality!
    }

    public void setMainMenuButtonListener(ActionListener listener){
        menuButton.addActionListener(listener);
    }
}

我希望有人能指出我犯的错误——不管我觉得自己多么愚蠢。

此外，我们将不胜感激任何其他反馈。正如我所说，这是我第一次编写 GUI，我必须说我有时会感到很迷茫。

Answer 1

 cardL.show(basePanel, "2");

面板的名称不是“2”。

您定义变量 MAINMENU 和 GAME 来表示每个面板的名称。

Answer 2

在您的 MainMenuPanel 窗格中创建 JPanel...

的实例

public MainMenuPanel(){
    // A new panel
    panel = new JPanel();

    //For testing //TODO remove
    panel.setBackground(Color.BLACK);

    newGameButton = new JButton("New Game");
    quitButton = new JButton("Quit");

    //New Game -button
    newGameButton.setPreferredSize(new Dimension(200, 100));
    newGameButton.setFont(menuFont);

    //Quit-button
    quitButton.setPreferredSize(new Dimension(200, 100));
    quitButton.setFont(menuFont);

    panel.setLayout(menuLayout);
    c1.insets = new Insets(10, 10, 10, 10);
    c1.gridx = 0;
    c1.gridy = 1;
    panel.add(newGameButton, c1);
    c1.gridx = 0;
    c1.gridy = 2;
    panel.add(quitButton, c1);
    // But what do you do with panel??
}

但永远不要将它添加到您的 MainMenuPanel...

你也在你的 GameMenu...

中做同样的事情

 public GameViewPanel(){

    // Create JPanel...
    JPanel gameViewPanel = new JPanel();

    gameViewPanel.setLayout(bordL);
    gameViewPanel.setBorder(new EmptyBorder(10, 10, 10, 10)); 

    //Creating toolbar
    JToolBar toolbar = new JToolBar();
    toolbar.setFloatable(false);

    gameViewPanel.setLayout(bordL);
    gameViewPanel.setBorder(new EmptyBorder(10, 10, 10, 10)); 
    gameViewPanel.add(toolbar, BorderLayout.PAGE_START);        

    //Buttons
    lopetaButton = new JButton("Lopeta");
    menuButton = new JButton("Päävalikko");
    tallennaButton = new JButton("Tallenna");

    //Adding buttons to game view toolbar
    toolbar.add(lopetaButton); //TODO Add functionality!
    toolbar.add(tallennaButton); //TODO Add functionality!
    toolbar.add(menuButton); //TODO Add functionality!
    // But never do anything with it...
}

我的建议是，不要。 MainMenuPanel 和 GameMenu 都是从 JPanel 扩展而来的，只需直接在这些面板之上创建 UI。似乎不需要这些 "inner" 面板...

Answer 3

好吧，当我继续做其他事情时，我实际上自己找到了答案。当我在研究一些布局设计时，我看到了 this 段代码并萌生了在我的面板类.

中使用“this”引用的想法

所以我从MainMenuPanel和GameviewPanel

中删除了这段代码

// A new panel
panel = new JPanel();

然后用 this 替换对该面板的引用。来自 MainMenuPanel 的示例：

this.setLayout(menuLayout);
c1.insets = new Insets(10, 10, 10, 10);
c1.gridx = 0;
c1.gridy = 1;
this.add(newGameButton, c1);
c1.gridx = 0;
c1.gridy = 2;
this.add(quitButton, c1);

我不能说我完全理解为什么这种方法行得通而另一种方法行不通，但是现在，我只需要一个可行的解决方案。我希望有一天这对其他人也有用。

CardLayout，来自单独 class 的面板未显示

CardLayout, panels from separate class not showing

java

user-interface

swing

cardlayout