可以使用MenuListener将弹出菜单的位置重置为显示在菜单上方：

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

public class MenuPopupUpListener implements MenuListener
{
    @Override
    public void menuSelected(MenuEvent e)
    {
        SwingUtilities.invokeLater(() ->
        {
            JMenu menu = (JMenu)e.getSource();
            JPopupMenu popup = menu.getPopupMenu();

            Rectangle bounds = popup.getBounds();
            Point location = menu.getLocationOnScreen();

            location.y -= bounds.getHeight();
            popup.setLocation(location);
        });
    }

    @Override
    public void menuCanceled(MenuEvent e) {}

    @Override
    public void menuDeselected(MenuEvent e) {}

    private static void createAndShowGUI()
    {
        JMenuBar menuBar = new JMenuBar();
        JMenu menu = new JMenu("Menu 1");
        menuBar.add( menu );

        menu.add( new JMenuItem( "MenuItem 1a" ) );
        menu.add( new JMenuItem( "MenuItem 1b" ) );
        menu.add( new JMenuItem( "MenuItem 1c" ) );

        //  Add a listener to all menus to have the popup open above the menu

        MenuListener ml = new MenuPopupUpListener();
        menu.addMenuListener( ml );

        JFrame frame = new JFrame("MenuPopupUp");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(menuBar, BorderLayout.PAGE_END);
        frame.setLocationByPlatform( true );
        frame.setSize(300, 300);
        frame.setVisible( true );
    }

    public static void main(String[] args)
    {
        java.awt.EventQueue.invokeLater( () -> createAndShowGUI() );
    }
}

侦听器需要添加到所有菜单中。