gridwidth 和 gridheight 如何工作（Java guid GridBagLayout）？

Question

我制作了 5 个简单的按钮来查看 GridBagLayout 约束是如何工作的，并将它们设置成十字形。我尝试尝试北方的网格宽度，gbc.gridwidth = 2; （因为默认是 0，然后是 1 和 2，它们是 3 列）准确地说。它不应该在 North 按钮所在位置的 x 轴上占据 3 列吗？但是当你运行它时，按钮都会重叠。请帮忙解释一下是什么问题？谢谢

    JPanel jp = new JPanel(new GridBagLayout());
    GridBagConstraints gbc = new GridBagConstraints();

    JButton jb1 = new JButton("North");
    gbc.gridx = 0;
    gbc.gridy = 0;
    gbc.gridwidth = 2; //Here, it won't take up three columns just at the top where it sits
    jp.add(jb1, gbc);

    JButton jb2 = new JButton("West");
    gbc.gridx = 0;
    gbc.gridy = 1;
    jp.add(jb2, gbc);

    JButton jb3 = new JButton("Center ");
    gbc.gridx = 1;
    gbc.gridy = 1;
    jp.add(jb3, gbc);

    JButton jb4 = new JButton("East");
    gbc.gridx = 2;
    gbc.gridy = 1;
    jp.add(jb4, gbc);

    JButton jb5 = new JButton("South");
    gbc.gridx = 1;
    gbc.gridy = 2;
    jp.add(jb5, gbc);

    add(jp);

    setVisible(true);

Answer 1

核心问题是，你没有重置约束……

JButton jb1 = new JButton("North");
gbc.gridx = 0;
gbc.gridy = 0;
gbc.gridwidth = 2; //Here, it won't take up three columns just at the top where it sits
jp.add(jb1, gbc);

JButton jb2 = new JButton("West");
// Still using the gridwidth value from before...
gbc.gridx = 0;
gbc.gridy = 1;
jp.add(jb2, gbc);

这意味着对于所有其他控件，gridwidth 的值仍设置为 2...

在添加jb1 后尝试添加gbc = new GridBagConstraints();。

另外，由于某种原因，gridwidth 不是零索引，它从 1 开始，所以您可能想改用 3...

JButton jb1 = new JButton("North");
gbc.gridx = 0;
gbc.gridy = 0;
gbc.gridwidth = 3; //Here, it won't take up three columns just at the top where it sits
jp.add(jb1, gbc);

gbc = new GridBagConstraints();
JButton jb2 = new JButton("West");
gbc.gridx = 0;
gbc.gridy = 1;
jp.add(jb2, gbc);

现在，我可能是错的，但您似乎试图让北按钮控制整个上排，类似于...

为此，您需要...

JButton jb1 = new JButton("North");
gbc.gridx = 0;
gbc.gridy = 0;
gbc.gridwidth = 3; //Here, it won't take up three columns just at the top where it sits
gbc.fill = GridBagConstraints.HORIZONTAL;
jp.add(jb1, gbc);

还有……