JMenu上的Actionlistener无法正常工作

Question

我有一个JMenu，并向其中添加了一个Actionlistener，但Action侦听器不执行任何操作。

我正在尝试使mnExit菜单退出程序（System.exit（0）），但Actionlistener却不执行任何操作。

谁能说出我做错了什么？

import java.io.IOException;


public class Main {
private int a;
private Server s;
private Client c;
private JFrame j;
private static JTextField ipClient;
private static JTextField hostPort;
private static JTextField portClient;
private static JPasswordField passwordClient;
private static JPasswordField passwordHost;
/**
 * @param args
 * @wbp.parser.entryPoint
 */
public static void main(String[] args) {
    // TODO Auto-generated method stub

    Main start=new Main();
    JFrame j=new JFrame("IControl");
    j.setSize(new Dimension(448, 291));
    j.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    j.setSize(700,700);
    j.getContentPane().setLayout(null);

    JButton clientButton = new JButton("connect to server");
    clientButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            Client c=new Client("localhost","bbc");
        }
    });
    clientButton.setBounds(32, 209, 154, 23);
    j.getContentPane().add(clientButton);

    JButton serverButton = new JButton("wait for connection");
    serverButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            Server s=new Server("abc");
        }
    });
    serverButton.setBounds(278, 209, 154, 23);
    j.getContentPane().add(serverButton);

    ipClient = new JTextField();
    ipClient.setBounds(67, 96, 123, 20);
    j.getContentPane().add(ipClient);
    ipClient.setColumns(10);

    hostPort = new JTextField();
    hostPort.setBounds(298, 130, 86, 20);
    j.getContentPane().add(hostPort);
    hostPort.setColumns(10);

    JLabel lblIp = new JLabel("IP");
    lblIp.setBounds(25, 99, 32, 14);
    j.getContentPane().add(lblIp);

    JLabel lblPort = new JLabel("port");
    lblPort.setBounds(25, 133, 32, 14);
    j.getContentPane().add(lblPort);

    portClient = new JTextField();
    portClient.setBounds(67, 130, 86, 20);
    j.getContentPane().add(portClient);
    portClient.setColumns(10);

    passwordClient = new JPasswordField();
    passwordClient.setBounds(67, 161, 86, 20);
    j.getContentPane().add(passwordClient);

    passwordHost = new JPasswordField();
    passwordHost.setBounds(298, 161, 86, 20);
    j.getContentPane().add(passwordHost);

    JLabel lblPass = new JLabel("pass");
    lblPass.setBounds(32, 158, 32, 14);
    j.getContentPane().add(lblPass);



    JMenuBar menuBar = new JMenuBar();
    menuBar.setBounds(0, 0, 93, 21);
    j.getContentPane().add(menuBar);

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

    JMenu mnExit = new JMenu("Exit");
    mnExit.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
             System.exit(0);
        }
    });
    mnFile.add(mnExit);


    j.setVisible(true);

//  j.pack();
}
/**
 * @wbp.parser.entryPoint
 */
public Main()
{

}

}

Answer 1

您必须更改代码行

JMenu mnExit = new JMenu("Exit");

到

JMenuItem mnExit = new JMenuItem("Exit");

因为您定义JMenu而不是定义JMenuItem，但不要忘记创建JMenu然后放在那里JMenuItem，有关JMenu / JMenuItem的教程中有更多内容