GridBagLayout - 我怎样才能让这个单元格填充它下面的空间？

Question

我正在创建一个带有 4 个 JPanel 的 JFrame。使用 GridBagLayout，我创建了三行两列，每列两个面板。通过将蓝色面板的单元格高度从 1 更改为 2，我可以使其覆盖其下方的单元格。我想对绿色面板做同样的事情，以填充它下面的空间。这是我的代码当前生成的内容：

我尝试将绿色面板的 gridheight 更改为 2，但结果如下：

我是否错误地使用了 GridBagLayout？这样做的适当方法是什么？

这是我的代码：

import java.awt.Color;
import java.awt.Container;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Main {

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        addComponents(frame.getContentPane());
        frame.setSize(800, 600);
        frame.setVisible(true);
    }

    public static void addComponents(Container contentPane) {
        contentPane.setLayout(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();
        c.insets = new Insets(3,3,3,3);
        c.fill = GridBagConstraints.BOTH;

        c.gridx = 0;
        c.gridy = 0;
        c.gridwidth = 1;
        c.gridheight = 2;
        c.weightx = 1;
        c.weighty = 0.85;
        JPanel panel1 = new JPanel();
        panel1.setBackground(Color.BLUE);
        contentPane.add(panel1, c);

        c.gridx = 0;
        c.gridy = 2;
        c.gridwidth = 1;
        c.gridheight = 1;
        c.weightx = 1.1;
        c.weighty = 0.35;
        JPanel panel2 = new JPanel();
        panel2.setBackground(Color.YELLOW);
        contentPane.add(panel2, c);

        c.gridx = 1;
        c.gridy = 0;
        c.gridwidth = 1;
        c.gridheight = 1;
        c.weightx = 0.15;
        c.weighty = 0.5;
        JPanel panel3 = new JPanel();
        panel3.setBackground(Color.RED);
        contentPane.add(panel3, c);

        c.gridx = 1;
        c.gridy = 1;
        c.gridwidth = 1;
        c.gridheight = 1;
        c.weightx = 0.38;
        c.weighty = 0.5;
        JPanel panel4 = new JPanel();
        panel4.setBackground(Color.GREEN);
        contentPane.add(panel4, c);
    }
}

Answer 1

我创建了三行两列，

实际上，您只有两行，因为您只添加了 gridy 值为 0 和 1 的组件。其中一个组件的 gridheight 为 2 的事实不会创建新行。

一种解决方案是使用嵌套面板。

为蓝色和黄色组件创建一个面板。这将使用一列两行的 GridBagLayout。然后为每个组件设置权重值以提供所需的高度。

然后您再次为红色和绿色组件创建第二个面板，其中包含 1 列和 2 行。每个权重将设置为 0.5。

最后，您创建了具有 2 列和 1 行的第三个面板。您设置所需的 weightx 并将上述两个面板添加到此面板，然后将面板添加到框架。

Answer 2

如果第 3 列包含三个单元格，则布局开始按预期运行，每个单元格的行跨度为 1。

import java.awt.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;

public class AnotherFourPanelLayout {

    private JComponent ui = null;

    AnotherFourPanelLayout() {
        initUI();
    }

    public void initUI() {
        if (ui != null) {
            return;
        }

        ui = new JPanel(new BorderLayout(4, 4));
        ui.setBorder(new EmptyBorder(4, 4, 4, 4));

        addComponents(ui);
    }

    public void addComponents(Container contentPane) {
        contentPane.setLayout(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();
        c.insets = new Insets(3, 3, 3, 3);
        c.fill = GridBagConstraints.BOTH;

        c.gridx = 0;
        c.gridy = 0;
        c.gridwidth = 1;
        c.gridheight = 2;
        c.weightx = 0.66;
        c.weighty = 0.66;
        JPanel panel1 = new JPanel();
        addLabel(panel1, c);
        panel1.setBackground(Color.CYAN);
        contentPane.add(panel1, c);

        c.gridx = 0;
        c.gridy = 2;
        c.gridwidth = 1;
        c.gridheight = 1;
        //c.weightx = 1.1; // logical?
        c.weightx = 0.66; 
        c.weighty = 0.33;
        JPanel panel2 = new JPanel();
        addLabel(panel2, c);
        panel2.setBackground(Color.YELLOW);
        contentPane.add(panel2, c);

        c.gridx = 1;
        c.gridy = 0;
        c.gridwidth = 1;
        c.gridheight = 1;
        c.weightx = 0.33;
        c.weighty = 0.33;
        JPanel panel3 = new JPanel();
        addLabel(panel3, c);
        panel3.setBackground(Color.RED);
        contentPane.add(panel3, c);

        c.gridx = 1;
        c.gridy = 1;
        c.gridwidth = 1;
        c.gridheight = 2;
        c.weightx = 0.33;
        c.weighty = 0.66;
        JPanel panel4 = new JPanel();
        addLabel(panel4, c);
        panel4.setBackground(Color.GREEN);
        contentPane.add(panel4, c);

        // hack to fix?
        c.gridx = 2;
        c.gridy = 0;
        c.gridwidth = 1;
        c.gridheight = 1;
        c.weightx = 0.01;
        c.weighty = 0.33;
        JPanel panelH1 = new JPanel();
        //addLabel(panelH1, c);
        panelH1.setBackground(Color.MAGENTA);
        contentPane.add(panelH1, c);

        c.gridy = 1;
        JPanel panelH2 = new JPanel();
        //addLabel(panelH2, c);
        panelH2.setBackground(Color.MAGENTA);
        contentPane.add(panelH2, c);

        c.gridy = 2;
        JPanel panelH3 = new JPanel();
        //addLabel(panelH3, c);
        panelH3.setBackground(Color.MAGENTA);
        contentPane.add(panelH3, c);
    }

    private void addLabel(JPanel panel, GridBagConstraints gbc) {
        panel.add(new JLabel(constraintsToString(gbc)));
    }

    private String constraintsToString(GridBagConstraints gbc) {
        StringBuilder sb = new StringBuilder();

        sb.append("<html><table>");
        sb.append(addRowToTable("Grid X", gbc.gridx));
        sb.append(addRowToTable("Grid Y", gbc.gridy));
        sb.append(addRowToTable("Weight X", gbc.weightx));
        sb.append(addRowToTable("Weight Y", gbc.weighty));
        sb.append(addRowToTable("Grid Width", gbc.gridwidth));
        sb.append(addRowToTable("Grid Height", gbc.gridheight));

        return sb.toString();
    }

    private String addRowToTable(String label, double value) {
        StringBuilder sb = new StringBuilder("<tr><td>");

        sb.append(label);
        sb.append("</td><td>");
        sb.append(value);
        sb.append("</td></tr>");


        return sb.toString();
    }

    public JComponent getUI() {
        return ui;
    }

    public static void main(String[] args) {
        Runnable r = new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception useDefault) {
                }
                AnotherFourPanelLayout o = new AnotherFourPanelLayout();

                JFrame f = new JFrame(o.getClass().getSimpleName());
                f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                f.setLocationByPlatform(true);

                f.setContentPane(o.getUI());
                f.pack();
                f.setMinimumSize(f.getSize());

                f.setVisible(true);
            }
        };
        SwingUtilities.invokeLater(r);
    }
}