java - GridBagConstraints无法正确对齐JRadioButton框

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，但始终将其设置在屏幕中央。以下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);
}

最佳答案

您将GridBagLayout提供给contentPane，但在不添加GridBagConstraints的情况下向其添加组件，然后不对面板JPanel提供任何布局，以便它使用默认的FlowLayout，并使用GridBagConstraints向其添加组件，这些约束无意义在这个情况下。

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

实际上，如果您需要的只是左上角的JRadioButtons集合，那么我将简单地删除面板JPanel：

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());
    }
}