如何修复JPopupMenu隐藏在边框内？

Question

我需要在对话框中显示菜单。然而，当JPopupMenu隐藏在边框中时，当barder插入很大时。

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

public class PopupMenuBorderInsetsBug {
    public static void main(String[] args) {
        JDialog popupDialog = new JDialog();
        popupDialog.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
        popupDialog.getRootPane().setBorder(new BorderWithInsets(Color.RED));

        JButton btnShowMenu = new JButton("Show Menu");

        JPopupMenu menu = new JPopupMenu();
        menu.add(new JMenuItem("Menu Item"));

        btnShowMenu.addActionListener(e -> menu.show(btnShowMenu, 0, btnShowMenu.getHeight()));
        popupDialog.add(btnShowMenu);

        popupDialog.pack();
        popupDialog.setVisible(true);
    }

    private static class BorderWithInsets extends LineBorder {
        public BorderWithInsets(Color color) {
            super(color);
        }

        @Override
        public Insets getBorderInsets(Component c) {
            return new Insets(10, 10, 30, 10);
        }
    }
}

上面的代码创建了一个对话框，当点击按钮时，菜单应该会出现，但它会隐藏在边框内。像这样

如果边框的插入被更改，因为返回新的插入（10,10,10,10）；时，菜单会显示，不会有任何问题。像这样

Answer 1

问题是由于根窗格的错误使用，您必须将组件放在JDialog的ContentPane中。

请参阅main中的更改：

public static void main(String[] args) {
    JDialog popupDialog = new JDialog();
    popupDialog.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);

    //Use a JPanel as container and set insets and content on it
    JPanel content=new JPanel();
    content.setBorder(new BorderWithInsets(Color.RED));

    JButton btnShowMenu = new JButton("Show Menu");

    JPopupMenu menu = new JPopupMenu();
    menu.add(new JMenuItem("Menu Item"));

    btnShowMenu.addActionListener(e -> menu.show(btnShowMenu, 0, btnShowMenu.getHeight()));
    
    content.add(btnShowMenu);

    //Set the panel as contentPane for the dialog
    popupDialog.setContentPane(content);
    popupDialog.pack();
    popupDialog.setVisible(true);
}