GridBagLayout不服从gridx和gridy

Question

我无法在正在制作的游戏中正确布置一些组件。我的GUI由一个带有BorderLayout的外部JFrame组成，而在BorderLayout的东侧，我有一个带有GridBagLayout的JPanel。我试图在JPanel中设置4个按钮（最后是其他一些东西 - 但我将它切换到按钮，当它不工作时），其gridx和gridy值设置为2行2列。但是，由于某种原因，它不起作用。它不是将按钮放在两行和列中，而是只显示一个按钮（screenshot）。

这是我的代码：

private class SidePanel extends JPanel
{
    private GridLayout sidePaneLayout;

    private JButton startButton;
    private JButton quitButton;
    private JButton saveButton;
    private JButton loadButton;
    private ButtonHandler buttonHandler;

    private JLabel stardate;
    private JLabel condition;
    private JLabel position;
    private JLabel warpFactor;
    private JLabel energy;
    private JLabel torpedos;
    private JLabel shields;
    private JLabel klingonsLeft;

    private JPanel statusPanel;


    public SidePanel()
    {
        super();

        this.setLayout(new GridBagLayout());
        GridBagConstraints constraints = new GridBagConstraints();



        startButton = new JButton("New Game");
        constraints.gridx = 0;
        constraints.gridy = 0;
        this.add(startButton, constraints);

        quitButton = new JButton("Quit Game");
        constraints.gridx = 0;
        constraints.gridy = 1;
        this.add(startButton, constraints);

        saveButton = new JButton("Save Game");
        constraints.gridx = 1;
        constraints.gridy = 0;
        this.add(startButton, constraints);

        loadButton = new JButton("Load Game");
        constraints.gridx = 1;
        constraints.gridy = 1;
        this.add(startButton, constraints);


        /*Dimension buttonSize = new Dimension(155, 60);

        startButton.setPreferredSize(buttonSize);
        quitButton.setPreferredSize(buttonSize);
        saveButton.setPreferredSize(buttonSize);
        loadButton.setPreferredSize(buttonSize);*/

        stardate = new JLabel("Stardate: ");
        condition = new JLabel("Condition: ");
        position = new JLabel("Position: ");
        warpFactor = new JLabel ("Warp Factor: ");
        energy = new JLabel("Energy: ");
        torpedos = new JLabel("Torpedos: ");
        shields = new JLabel("Shields: ");
        klingonsLeft = new JLabel("Klingons Left: ");

        statusPanel = new JPanel(new GridLayout(0, 2));





        statusPanel.add(stardate);
        statusPanel.add(condition);
        statusPanel.add(position);
        statusPanel.add(warpFactor);
        statusPanel.add(energy);
        statusPanel.add(torpedos);
        statusPanel.add(shields);
        statusPanel.add(klingonsLeft);

        constraints.gridx = 0;
        constraints.gridy = 2;
        //this.add(statusPanel, constraints);
    }

知道为什么这不起作用？我已经在独立的JFrame中使用GridBagLayout完成了一些其他测试，它们都可以正常工作。但是当我尝试在这个程序的内部JPanel中使用它时，它失败了。

Answer 1

您正在添加startButton按钮4次，这就是为什么它只显示一次。

 this.add(startButton, constraints);

---

现在经过一些修正后，它看起来如下所示。

constraints.insets=new Insets(5, 5, 5, 5);// add top, left, bottom, right insets
...
constraints.gridx = 0;
constraints.gridy = 2;
constraints.gridwidth=2; // span two column
this.add(statusPanel, constraints);

Answer 2

将代码更改为此（即使1个对象错误，网格包也很敏感！）：

    startButton = new JButton("New Game");
    constraints.gridx = 0;
    constraints.gridy = 0;
    this.add(startButton, constraints);

    quitButton = new JButton("Quit Game");
    constraints.gridx = 0;
    constraints.gridy = 1;
    this.add(quitButton , constraints);

    saveButton = new JButton("Save Game");
    constraints.gridx = 1;
    constraints.gridy = 0;
    this.add(saveButton , constraints);

    loadButton = new JButton("Load Game");
    constraints.gridx = 1;
    constraints.gridy = 1;
    this.add(loadButton , constraints);