java - 如何将 BorderLayout 放入 CardLayout 中？

Question

问题可能不正确，但我不知道如何正确提问。对此我感到很抱歉。

问题在这里:

我的 JFrame 将 CardLayout 作为布局管理器。我有三个 JPanel，我在它们之间切换。一切都很好，直到我不得不将 2 个 JPanel 添加到其中一个中。现在，我的一个 JPanel 应该包含另外两个 JPanel。我在某处读到这是可能的。所以这个JPanel应该有BorderLayout。应该是这样的:

这是我之前的:

• 我的JFrame类:

  public class JavaGame2 extends JFrame {
  
      public JavaGame2(){
  
          CardLayout layout = new CardLayout();
          setLayout(layout);
          GameController controller = new CardLayoutGameController(getContentPane(), layout);
  
          gamePanel = new GamePanel(controller);          
          menuPanel = new MenuPanel(controller);
          lvlPanel = new LvlEndPanel(controller);
  
          add(gamePanel, CardLayoutGameController.GAME_PANEL);
          add(menuPanel, CardLayoutGameController.MENU_PANEL);
          add(lvlPanel, CardLayoutGameController.LEVEL_PANEL);
  
  
          controller.showMenu();
  }
  

• CardLayoutGameController 正在切换所有 JPanel:

  public class CardLayoutGameController implements GameController {
      public static final String GAME_PANEL = "GamePanel";
      public static final String MENU_PANEL = "MenuPanel";
      public static final String LEVEL_PANEL = "LvlPanel";            
  
      private Container container;
      private CardLayout cardLayout;
  
      public CardLayoutGameController(Container parent, CardLayout layout) {
          container = parent;
          cardLayout =  layout;
      }
  
      @Override
      public void showMenu() {
          cardLayout.show(container, MENU_PANEL);
      }
  
      @Override
      public void showGame() {
          cardLayout.show(container, GAME_PANEL);
      }
  
      @Override
      public void showEndLvl(){
          cardLayout.show(container, LEVEL_PANEL);
      }
  }
  

然后我添加了两个 JPanel 类 InterfacePanel 和 GameMainPanel(其中应该包括这个 InterfacePanel 和我的旧游戏面板)

现在的样子:

UPD可运行示例:

• 可运行类:

  public class Mcve extends JFrame {
  
      private GamePanel gamePanel;
      private LvlEndPanel lvlPanel;
      private GameMainPanel gameMainPanel;
  
  
      Mcve(){
          CardLayout layout = new CardLayout();
  
          setLayout(layout);
          GameController controller = new CardLayoutGameController(getContentPane(), layout);
  
          gamePanel = new GamePanel(controller);  
          lvlPanel = new LvlEndPanel(controller);
          gameMainPanel = new GameMainPanel(controller,this.getContentPane());
  
          add(gamePanel, CardLayoutGameController.GAME_PANEL);
          add(lvlPanel, CardLayoutGameController.LEVEL_PANEL);
          add(gameMainPanel, CardLayoutGameController.GAME_MAIN_PANEL);
          controller.showMenu();
  
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          pack();
          setLocationRelativeTo(null);
          setTitle("JavaGame2");
          setResizable(false); 
      }
      /**
       * @param args the command line arguments
       */
      public static void main(String[] args) {
          EventQueue.invokeLater(new Runnable() {
              public void run() {
                  JFrame jgame = new Mcve();
                  jgame.setVisible(true);
              }
          });
      }
  }
  

• 游戏 Controller :

  public interface GameController {
      public void showMenu();
      public void showGame();
      public void showEndLvl();
  }
  

• CardLayoutGameController:

  public class CardLayoutGameController implements GameController {
      public static final String MENU_PANEL = "MenuPanel";
      public static final String LEVEL_PANEL = "LvlPanel";
      public static final String GAME_MAIN_PANEL = "GameMainPanel";
  
      private Container container;
      private CardLayout cardLayout;   
  
      public CardLayoutGameController(Container parent, CardLayout layout) {
          container = parent;
          cardLayout =  layout;        
      }
  
      @Override
      public void showMenu() {
          cardLayout.show(container, MENU_PANEL);
      }
  
      @Override
      public void showGame() {
          cardLayout.show(container, GAME_MAIN_PANEL);        
      }
  
      @Override
      public void showEndLvl(){
          cardLayout.show(container, LEVEL_PANEL);
      }
  }
  

• GameMainPanel - 包括 2 个 JPanel:

  public class GameMainPanel extends JPanel {
  
      private Container container;
      private GameController controller;
      private BorderLayout layout;
  
      private GamePanel gamePanel;
      private InterfacePanel interfacePanel;
  
      GameMainPanel(GameController contrl,Container parent){
          controller = contrl;
          container = parent;
          setFocusable(true);
          setBackground(Color.WHITE);
          getPreferredSize();
  
          gamePanel = new GamePanel(contrl);
          interfacePanel = new InterfacePanel(contrl);
  
          layout = new BorderLayout();
          setLayout(layout);
          add(gamePanel, BorderLayout.LINE_START);
          add(interfacePanel, BorderLayout.LINE_END);
  
          addComponentListener(new ComponentAdapter() {
                  public void componentShown(ComponentEvent e) {
                          requestFocusInWindow();
                  }
          });
      }
  
      @Override
      public void addNotify() {
          super.addNotify();
          requestFocusInWindow();
      }
  
       public void paint(Graphics g) {
          super.paint(g);
      }
  
      public Dimension getPreferredSize() {
          return new Dimension(800, 600);
      }
  
  }
  

• 游戏面板:

  public class GamePanel extends JPanel {
  
      private GameController controller;    
  
      public GamePanel (GameController contrl){        
          controller = contrl;
  
          addKeyListener(new GameAdapter(contrl));
          setFocusable(true);
          setBackground(Color.BLACK);
          getPreferredSize();        
          addComponentListener(new ComponentAdapter() {
  
                  public void componentShown(ComponentEvent e) {
                          requestFocusInWindow();
                  }
              });
      }
  
      @Override
      public void addNotify() {
          super.addNotify();
          requestFocusInWindow();
      }
  
      public Dimension getPreferredSize() {
          return new Dimension(650, 600);
      }
  
      @Override
      public void paint(Graphics g) {
          super.paint(g); 
          Graphics2D g2d = (Graphics2D)g;
  
          Font small = new Font("Helvetica", Font.BOLD, 24);
          FontMetrics metr = this.getFontMetrics(small);
          g.setColor(Color.GREEN);
          g.setFont(small);
          g.drawString("game",300,300);
      }
  
      private class GameAdapter extends KeyAdapter{
  
          private GameController controller;
  
          GameAdapter(GameController contrl){
              controller = contrl;
          }
          public void keyPressed(KeyEvent e) {
              if ((e.getKeyCode() == KeyEvent.VK_ENTER)) {
                  controller.showEndLvl();
              }             
          }
      }
  }
  

• 界面面板

  public class InterfacePanel extends JPanel {
  
      private GameController controller;    
  
      InterfacePanel(GameController contrl){
          setFocusable(true);
          setBackground(Color.WHITE);
          getPreferredSize();
          setSize(150,600);
  
          addComponentListener(new ComponentAdapter() {
                  public void componentShown(ComponentEvent e) {
                          requestFocusInWindow();
                  }
          });
      }
  
      @Override
      public void addNotify() {
          super.addNotify();
          requestFocusInWindow();
      }
  
       public void paint(Graphics g) {
          super.paint(g);
          Graphics2D g2d = (Graphics2D)g;
  
          Font small = new Font("Helvetica", Font.BOLD, 24);
          FontMetrics metr = this.getFontMetrics(small);
          g.setColor(Color.GREEN);
          g.setFont(small);
          g.drawString("interface",10,300);
      }
  
      public Dimension getPreferredSize() {
  
          return new Dimension(150, 600);
      }
  }
  

• LvlEndPanel:

  public class LvlEndPanel extends JPanel{
  
      private GameController controller;
  
      public LvlEndPanel(GameController contrl){
          controller = contrl;
  
          setFocusable(true);
          setBackground(Color.BLACK);
          getPreferredSize();           
          addComponentListener(new ComponentAdapter() {
  
                  public void componentShown(ComponentEvent e) {
                          requestFocusInWindow();
                  }
          });
  
          addKeyListener(new KeyListener() {
  
              @Override
              public void keyPressed(KeyEvent e) {
                  if ((e.getKeyCode() == KeyEvent.VK_ENTER)) {
                              controller.showMenu();
                      }                
              }
              @Override
              public void keyTyped(KeyEvent e) {                
              }
              @Override
              public void keyReleased(KeyEvent e) {                
              }
  
          });
      }
  
      @Override
      public void addNotify(){
          super.addNotify();
          requestFocusInWindow();        
      }
  
       public void paint(Graphics g) {
          super.paint(g);
          Graphics2D g2d = (Graphics2D)g;
  
          Font small = new Font("Helvetica", Font.BOLD, 24);
          FontMetrics metr = this.getFontMetrics(small);
          g.setColor(Color.GREEN);
          g.setFont(small);
          g.drawString("Level Panel",300,300);
      }
  
       public Dimension getPreferredSize() {        
          return new Dimension(800, 600);
      }
  }
  

• 菜单面板:

  public class MenuPanel extends JPanel{
  
      private GameController controller;
  
      public MenuPanel(GameController contrl){
  
          setFocusable(true);
          setBackground(Color.WHITE);
          getPreferredSize();
          controller = contrl;
  
          addComponentListener(new ComponentAdapter() {
                  public void componentShown(ComponentEvent e) {
                          requestFocusInWindow();
                  }
          });
  
          addKeyListener(new KeyListener() {
  
              @Override
              public void keyTyped(KeyEvent e) {
              }
  
              @Override
              public void keyPressed(KeyEvent e) {
                      if ((e.getKeyCode() == KeyEvent.VK_ENTER)) {
                          controller.showGame();
                      }
              }
  
              @Override
              public void keyReleased(KeyEvent e) {                
              }
  
          });
  
      }
  
      @Override
      public void addNotify() {
          super.addNotify();
          requestFocusInWindow();
      }
  
  
      public void paint(Graphics g) {
          super.paint(g);
          Graphics2D g2d = (Graphics2D)g;
  
          Font small = new Font("Helvetica", Font.BOLD, 24);
          FontMetrics metr = this.getFontMetrics(small);
          g.setColor(Color.GREEN);
          g.setFont(small);
          g.drawString("Game Menu", 300,300);
      }
  
      public Dimension getPreferredSize() {        
          return new Dimension(800, 600);
      }
  }
  

向上倾斜

当我启动这个时，我只有黑框。我怎样才能解决这个问题？我做错了什么？

提前致谢。

感谢您的编辑。

Answer 1

您的 Controller 定义 showMenu作为

public void showMenu() {
    cardLayout.show(container, MENU_PANEL);
}

但是你永远不会添加任何名称为 MENU_PANEL 的内容

add(gamePanel, CardLayoutGameController.GAME_PANEL);
add(lvlPanel, CardLayoutGameController.LEVEL_PANEL);
add(gameMainPanel, CardLayoutGameController.GAME_MAIN_PANEL);

更改 gameMainPanel 使用的名称至MENU_PANEL或更改 showMenu使用GAME_MAIN_PANEL相反

根据示例代码进行更新

实际上你的布局没有任何问题，(主要)问题是你的MenuPanel paint方法。如果可能，您应该避免在 paint 中加载字体。方法，加载字体的过程可能非常耗时，这会妨碍您的面板及时绘制。

相反，可以在构造函数中预加载字体，并在绘制时应用它，例如......

public class MenuPanel extends JPanel {
    //...
    public MenuPanel(GameController contrl) {
        //...
        Font small = new Font("Helvetica", Font.BOLD, 24);
        setFont(small);
    }

    public void paint(Graphics g) {
        super.paint(g);
        Graphics2D g2d = (Graphics2D) g;

        g.setFont(getFont());
        FontMetrics metr = g.getFontMetrics();
        g.setColor(Color.GREEN);
        g.drawString("Game Menu", 300, 300);
    }
}

这适用于LvlEndPanel , InterfacePanel ，和GamePanel还有...

旁注

• addNotify将不再按照您配置的方式工作，因为组件仅添加一次，而您应该依赖 ComponentListener (你就是)。更好的解决方案是使用 the key bindings API这可以让您克服 KeyListener 的焦点限制.
• 通常情况下，您会覆盖 paintComponent而不是paint 。 paint做了很多很容易被破坏的工作，并且其他子组件在重新绘制时可能会导致问题......