在menuSelected上更改JMenu前景色

Question

我有一个菜单，我想在点击它时更改它。

这是我的代码：

violatorMenu.addMenuListener(new MenuListener() {

            @Override
            public void menuSelected(MenuEvent e) {
                violatorMenu.setForeground(new java.awt.Color(255, 255, 255));
                violatorMenu.setBackground(new java.awt.Color(183, 28, 28));
            }

            @Override
            public void menuDeselected(MenuEvent e) {
           }

            @Override
            public void menuCanceled(MenuEvent e) {


            }
        });

此代码不会更改默认颜色。

有什么想法吗？感谢

Answer 1

尝试violatorMenu.setOpaque（true）。其余代码似乎工作正常。这是一个例子：

import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.event.MenuEvent;
import javax.swing.event.MenuListener;

public class MenuExample extends JFrame {

    private void createAndShowGUI() {
        /** the main frame */
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JMenuBar mb = new JMenuBar();
        setJMenuBar(mb);
        JMenu violatorMenu = new JMenu("A menu");
        JMenuItem mi = new JMenuItem("A menu item");
        violatorMenu.add(mi);
        violatorMenu.setOpaque(true);
        mb.add(violatorMenu);

        violatorMenu.addMenuListener(new MenuListener() {
            @Override
            public void menuSelected(MenuEvent e) {
                violatorMenu.setForeground(new java.awt.Color(255, 255, 255));
                violatorMenu.setBackground(new java.awt.Color(183, 28, 28));
            }
            @Override
            public void menuDeselected(MenuEvent e) {
            }
            @Override
            public void menuCanceled(MenuEvent e) {
            }
        });

        /** show the frame to the user */
        pack();
        setVisible(true);
    }

    public static void main(String[] args) {

        final MenuExample frame = new MenuExample();

        /** schedule for the event dispatcher */
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                frame.createAndShowGUI();
            }
        });
    }

}