java - GridBagConstraints 未正确对齐 JRadioButton 框

Question

即使指定了 .weightx、.weighty 和 .anchor，GridBagConstraints 也不起作用。我需要将组件设置在左上角，但它一直设置在屏幕中央。下面是我用于定位组件的方法。

private void initGUI(){
    getContentPane().setLayout(new GridBagLayout());

    JPanel panel = new JPanel();
    panel.setPreferredSize(new Dimension(450, 450));

    Box buttonBox = Box.createVerticalBox();
    ButtonGroup buttons = new ButtonGroup();

    buttons.add(okOnly);
    buttons.add(okCancel);
    buttons.add(yesNoCancel);
    buttons.add(yesNo);

    buttonBox.add(okOnly);
    buttonBox.add(okCancel);
    buttonBox.add(yesNoCancel);
    buttonBox.add(yesNo);
    buttonBox.setBorder(BorderFactory.createTitledBorder("Buttons"));

    GridBagConstraints gridConstraints = new GridBagConstraints();
    gridConstraints.gridx = 0;
    gridConstraints.gridy = 0;
    gridConstraints.anchor = GridBagConstraints.NORTHWEST;
    gridConstraints.weightx = 1;
    gridConstraints.weighty = 1;

    panel.add(buttonBox, gridConstraints);
    getContentPane().add(panel);
}

Answer 1

您将 GridBagLayout 赋予 contentPane，但向其添加一个不带 GridBagConstraints 的组件，然后向面板 JPanel 赋予 no 布局，以便它使用默认的 FlowLayout，并添加组件它使用 GridBagConstraints，在这种情况下没有意义的约束。

解决方案:显然不要这样做。仅在将组件添加到使用 GridBagLayout 的容器时使用 GridBagConstraints。

事实上，如果您只需要左上角的 JRadioButtons 集合，我会简单地去掉 JPanel 面板:

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

public class Gui extends JFrame {
    private JRadioButton okOnly = new JRadioButton("Ok ");
    private JRadioButton okCancel = new JRadioButton("Ok Cancel");
    private JRadioButton yesNoCancel = new JRadioButton("Yes No Cancel");
    private JRadioButton yesNo = new JRadioButton("Yes No");

    private void initGUI() {
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        getContentPane().setLayout(new GridBagLayout());

        // JPanel panel = new JPanel();
        // panel.setPreferredSize(new Dimension(450, 450));

        setPreferredSize(new Dimension(450, 450));

        Box buttonBox = Box.createVerticalBox();
        ButtonGroup buttons = new ButtonGroup();

        buttons.add(okOnly);
        buttons.add(okCancel);
        buttons.add(yesNoCancel);
        buttons.add(yesNo);

        buttonBox.add(okOnly);
        buttonBox.add(okCancel);
        buttonBox.add(yesNoCancel);
        buttonBox.add(yesNo);
        buttonBox.setBorder(BorderFactory.createTitledBorder("Buttons"));

        GridBagConstraints gridConstraints = new GridBagConstraints();
        gridConstraints.gridx = 0;
        gridConstraints.gridy = 0;
        gridConstraints.anchor = GridBagConstraints.NORTHWEST;
        gridConstraints.weightx = 1;
        gridConstraints.weighty = 1;

        // panel.add(buttonBox, gridConstraints);
        add(buttonBox, gridConstraints);
        // getContentPane().add(panel);

        pack();
        setLocationRelativeTo(null);
        setVisible(true);
    }

    private static void createAndShowGui() {
        new Gui().initGUI();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }
}