将组件的首选大小保持在 BorderLayout 的中心

Question

我有一个使用 BorderLayout 的中型 UI；中心是一个选项卡式窗格，包含具有各种布局等的各种面板。

我希望此边框布局中心的面板根据 窗口，但我不希望面板中的组件拉伸。标签、组合框、文本字段、按钮——我希望它们保持首选大小，并允许包含它们的面板伸展。我将它们放在滚动窗格中，以防面板空间太小。

各种带有彩色词汇的海报警告在组件上使用任何 setXXXsize() 方法的危险。这就是我现在所做的，我想学习如何避免它。

GridBagLayout 不适用于我的某些面板。它本质上是围绕行和列定向的，并不是所有的东西都适合行和列。当然，我可以创建人工行和列来适应所有内容，但我真的希望 Swing 有更多的布局选项。

Vertical Glue 也不行。我已将它包含在 HFOE 心爱的 SSCE 中：

    package example;

    import java.awt.BorderLayout;

    import javax.swing.Box;
    import javax.swing.BoxLayout;
    import javax.swing.JComboBox;
    import javax.swing.JFrame;
    import javax.swing.JLabel;
    import javax.swing.JPanel;

    public class BorderAndBox extends JFrame
    {
        public static void main(String args[])
        {
            BorderAndBox bnb = new BorderAndBox();
            bnb.createUI();
            bnb.setVisible(true);
        }

        public void createUI()
        {
            JPanel borderPanel = new JPanel(new BorderLayout());

            JLabel northLabel = new JLabel("Nawth");
            borderPanel.add(northLabel, BorderLayout.NORTH);

            String[] southComboChoices = { "one", "two", "three" };
            JComboBox southCombo = new JComboBox(southComboChoices);
            borderPanel.add(southCombo, BorderLayout.SOUTH);

            JPanel centerPanel = new JPanel();
            centerPanel.setLayout(new BoxLayout(centerPanel, BoxLayout.PAGE_AXIS));
            String[] firstChoices = { "first", "uno", "UN" };
            String[] secondChoices = { "second", "dos", "zwei" };
            String[] thirdChoices = { "third", "tres", "drei" };
            JComboBox firstCombo = new JComboBox(firstChoices);
            JComboBox secondCombo = new JComboBox(secondChoices);
            JComboBox thirdCombo = new JComboBox(thirdChoices);
            centerPanel.add(firstCombo);
            centerPanel.add(secondCombo);
            centerPanel.add(thirdCombo);
            centerPanel.add(Box.createVerticalGlue());  // first attempt; does NOT
            // take up available vertical space, instead it appears to create a space
            // that is shared equally among the (now) four components of this space.
            borderPanel.add(centerPanel, BorderLayout.CENTER);

            getContentPane().add(borderPanel);
            pack();
        }

    }

如果放大窗口，中心的组合框会放大；如前所述，它们下方的垂直胶块也会扩大，但不会占用所有可用空间。看起来它被赋予了和它们一样多的空间。

那么有什么好的方法来解决这个问题？

Answer 1

import java.awt.BorderLayout;
import java.awt.GridBagLayout;

import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class BorderAndBox extends JFrame
{
public static void main(String args[])
{
    BorderAndBox bnb = new BorderAndBox();
    bnb.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    bnb.createUI();
    bnb.setVisible(true);
}

public void createUI()
{
    JPanel borderPanel = new JPanel(new BorderLayout());

    JLabel northLabel = new JLabel("Nawth");
    borderPanel.add(northLabel, BorderLayout.NORTH);

    String[] southComboChoices = { "one", "two", "three" };
    JComboBox southCombo = new JComboBox(southComboChoices);
    borderPanel.add(southCombo, BorderLayout.SOUTH);

    JPanel centerPanel = new JPanel();
    centerPanel.setLayout(new BoxLayout(centerPanel, BoxLayout.PAGE_AXIS));
    String[] firstChoices = { "first", "uno", "UN" };
    String[] secondChoices = { "second", "dos", "zwei" };
    String[] thirdChoices = { "third", "tres", "drei" };
    JComboBox firstCombo = new JComboBox(firstChoices);
    JComboBox secondCombo = new JComboBox(secondChoices);
    JComboBox thirdCombo = new JComboBox(thirdChoices);
    centerPanel.add(firstCombo);
    centerPanel.add(secondCombo);
    centerPanel.add(thirdCombo);
    centerPanel.add(Box.createVerticalGlue());  // first attempt; does NOT
    // take up available vertical space, instead it appears to create a space
    // that is shared equally among the (now) four components of this space.
    JPanel centerPanelConstrain = new JPanel(new GridBagLayout());
    centerPanelConstrain.add(centerPanel);
    borderPanel.add(centerPanelConstrain, BorderLayout.CENTER);

    getContentPane().add(borderPanel);
    pack();
}

}

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另见this answer。解决这个问题的方法不止一种。

Answer 2

我建议您使用 JPanel 和 javax.swing.GroupLayout。然而，通过编码来使用这种布局并不容易。如果您不想使用 IDE，请使用 Netbeans Matisse Builder 等代码生成器并将其复制粘贴到您想要的任何位置。