java - 无法使 GridBagLayout 按预期工作

Question

/**
 *  I'd like to achive following layout:
 *   +----------+----------+
 *   | Button 1 |          |
 *   +----------| Button 2 |
 *   | Button 3 |          |
 *   +----------+----------+
 *  with following code:
 */

JPanel panel = new JPanel(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
JButton button;

button = new JButton("Button 1");
c.weightx = 0.5;
c.weighty = 0.5;
c.fill = GridBagConstraints.BOTH;
panel.add(button, c);

button = new JButton("Button 2");
c.gridwidth = GridBagConstraints.REMAINDER;
c.gridheight = 2;
panel.add(button, c);

button = new JButton("Button 3");
c.gridwidth = 1;
panel.add(button, c);

/**
 *  but what I achive is:
 *   +----------+----------+
 *   | Button 1 | Button 2 |
 *   +----------+----------+|
 *   | Button 3 |
 *   +----------+
 */

/**
 *  However layout:
 *   +----------+----------+
 *   |          | Button 2 |
 *   + Button 1 +----------+
 *   |          | Button 3 |
 *   +----------+----------+
 *  is easily achieved as:
 */

JPanel panel = new JPanel(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
JButton button;

button = new JButton("Button 1");
c.weightx = 0.5;
c.weighty = 0.5;
c.fill = GridBagConstraints.BOTH;
c.gridheight = 2;
panel.add(button, c);

button = new JButton("Button 2");
c.gridwidth = GridBagConstraints.REMAINDER;
c.gridheight = 1;
panel.add(button, c);

button = new JButton("Button 3");
panel.add(button, c);

有什么线索吗？

问候，弗朗西斯

Answer 1

需要指定gridx和gridy，默认为0。

    button = new JButton("Button 1");
    c.weightx = 0.5;
    c.weighty = 0.5;
    c.fill = GridBagConstraints.BOTH;
    panel.add(button, c);

    button = new JButton("Button 3");
    c.gridy = 1;
    c.gridwidth = 1;
    panel.add(button, c);

    button = new JButton("Button 2");
    c.gridx = 1; c.gridy = 0;
    c.gridwidth = GridBagConstraints.REMAINDER;
    c.weighty = 1;c.gridheight = 2;
    panel.add(button, c);