如何使用 GridBagLayout 强制 JPanel 使用 JFrame 调整大小

Question

当框架展开时，我需要展开 menuPanel 的组件。 MenuPanel 正在使用 GridBayLayout，我已经修改了面板的填充和权重值，但似乎没有什么真正导致组件随框架调整大小。

我怀疑我在显示类中添加 menuPanel 的方式有问题。此外，我还尝试为 TanksApplication 设置布局，但也没有用。我认为我没有理解一些基本的东西。

主应用

    public class TanksApplication extends JFrame{ 

       public TanksApplication(){
           super("Tanks");
       }

       public static void main (String args[]){
          Display display = new Display();
          TanksApplication frame = new TanksApplication();
          frame.add(display);
          frame.setSize(600,425);
          frame.setVisible(true);
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.setLocationRelativeTo(null);
       }
   }

显示类

public class Display extends JPanel{    
   public Display(){
       menuPanel = new JPanel(new GridBagLayout());
       GridBagConstraints con = new GridBagConstraints();

       mainMenuImageP = new JPanel();
       mainMenuImageP.setBackground(Color.BLACK);
       con.fill = GridBagConstraints.BOTH;
       con.gridy = 0;
       con.gridx = 0;
       con.gridwidth = 2;
       con.weightx = 0.5;
       con.weighty = 0.5;
       con.anchor = GridBagConstraints.CENTER;
       con.ipadx = 400;
       con.ipady = 300;
       con.insets = new Insets(0,20,0,20);
       menuPanel.add(mainMenuImageP, con);

       newGameB = new JButton("New Game");
       con.fill = GridBagConstraints.HORIZONTAL;
       con.gridy = 1;
       con.gridx = 0;
       con.gridwidth = 1;
       con.weightx = 0.5;
       con.weighty = 0.5;
       con.anchor = GridBagConstraints.CENTER;
       con.ipadx = 0;
       con.ipady = 0;
       con.insets = new Insets(10,10,10,10);
       menuPanel.add(newGameB, con);

       loadGameB = new JButton("Load Game");
       con.fill = GridBagConstraints.HORIZONTAL;
       con.gridy = 1;
       con.gridx = 1;
       con.gridwidth = 1;
       con.weightx = 0.5;
       con.weighty = 0.5;
       con.anchor = GridBagConstraints.CENTER;
       con.ipadx = 0;
       con.ipady = 0;
       con.insets = new Insets(10,10,10,10);
       menuPanel.add(loadGameB, con);

       add(menuPanel);
   }

Answer 1

您的问题是您使用 menuPanel 将 GridBagLayout 添加到 Display JPanel 中，后者使用 JPanel 的默认 FlowLayout。 FlowLayout 不会调整添加到其中的组件的大小。解决方案：摆脱 menuPanel，只使用Display JPanel。给它一个 GridBagLayout 并向其中添加组件。

在 Display 的构造函数中也是如此

setLayout(new GridBagLayout());

删除JPanel menuPanel = new JPanel();和任何你有menuPane.add(...);的地方，把它改成简单的add(...)；

例如，

public class Display extends JPanel{    
    public Display(){
        // !! menuPanel = new JPanel(new GridBagLayout());
        GridBagConstraints con = new GridBagConstraints();

        mainMenuImageP = new JPanel();
        mainMenuImageP.setBackground(Color.BLACK);
        con.fill = GridBagConstraints.BOTH;
        con.gridy = 0;
        con.gridx = 0;
        con.gridwidth = 2;
        con.weightx = 0.5;
        con.weighty = 0.5;
        con.anchor = GridBagConstraints.CENTER;
        con.ipadx = 400;
        con.ipady = 300;
        con.insets = new Insets(0,20,0,20);
        // !! menuPanel.add(mainMenuImageP, con);
        add(mainMenuImageP, con); // !!

        newGameB = new JButton("New Game");
        con.fill = GridBagConstraints.HORIZONTAL;
        con.gridy = 1;
        con.gridx = 0;
        con.gridwidth = 1;
        con.weightx = 0.5;
        con.weighty = 0.5;
        con.anchor = GridBagConstraints.CENTER;
        con.ipadx = 0;
        con.ipady = 0;
        con.insets = new Insets(10,10,10,10);
        // !! menuPanel.add(newGameB, con);
        add(newGameB, con); // !!

        loadGameB = new JButton("Load Game");
        con.fill = GridBagConstraints.HORIZONTAL;
        con.gridy = 1;
        con.gridx = 1;
        con.gridwidth = 1;
        con.weightx = 0.5;
        con.weighty = 0.5;
        con.anchor = GridBagConstraints.CENTER;
        con.ipadx = 0;
        con.ipady = 0;
        con.insets = new Insets(10,10,10,10);
        // !! menuPanel.add(loadGameB, con);
        add(loadGameB, con); // !!

        // !! add(menuPanel);
    }

}

请注意，如果这没有帮助，请考虑创建并发布 minimal example program 或 SSCCE。