java使二级菜单栏点击出现一个窗口，没反应，事件处理如何处理？

Question

package FakeMenu;

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;
import javax.swing.JMenuBar;
import javax.swing.JMenu;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;

public class FakeMenu extends JFrame {

/**
 * 
 */
private static final long serialVersionUID = 1L;
private JPanel contentPane;
JTextField t;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                FakeMenu frame = new FakeMenu();
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the frame.
 */
public FakeMenu() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 450, 308);

    JMenuBar menuBar = new JMenuBar();
    setJMenuBar(menuBar);

    JMenu mnFile = new JMenu("File");
    menuBar.add(mnFile);

    JMenu mnNewMenu_1 = new JMenu("New");
    mnNewMenu_1.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            JOptionPane.showMessageDialog(null, "ada");
        }
    });
    mnFile.add(mnNewMenu_1);

    JMenu mnNewMenu_2 = new JMenu("Open");
    mnFile.add(mnNewMenu_2);

    JMenu mnSave_1 = new JMenu("Save");
    mnFile.add(mnSave_1);

    JMenu mnNewMenu = new JMenu("Edit");
    menuBar.add(mnNewMenu);

    JMenu mnCopy = new JMenu("Copy");
    mnNewMenu.add(mnCopy);

    JMenu mnCut = new JMenu("Cut");
    mnNewMenu.add(mnCut);

    JMenu mnNewMenu_3 = new JMenu("Paste");
    mnNewMenu.add(mnNewMenu_3);

    JMenu mnSave = new JMenu("Help");
    menuBar.add(mnSave);

    JMenu mnAbout = new JMenu("About");
    mnSave.add(mnAbout);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    contentPane.setLayout(new BorderLayout(0, 0));
    setContentPane(contentPane);
}

}

Answer 1

https://zhidao.baidu.com/question/326640458278816525.html