菜单项不会响应点击

Question

the "Exit" MenuItem responds perfectly but the "Change Name" is a problem.. i can't figure out whats wrong, Can Someone help please... I know the userName.setUserName is working ok.. cuz i'm using it in another class and it works perfectly. just can't figure out whats wrong

Here's the code

public class MenuBar extends JMenuBar{

    // variable declaration
    private JMenu menu;
    private JMenuItem menuItem;
    private JMenuItem changed_Name;
    private JMenuItem exit;



    public MenuBar(){

        init();

    }


    private void init(){

       menu = new JMenu("File");
       add(menu);

       changed_Name = new JMenuItem("Change Name");
       changed_Name.setMnemonic(KeyEvent.VK_C);
       changed_Name.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_1, KeyEvent.ALT_MASK));
       changed_Name.getAccessibleContext().setAccessibleDescription("This Will Allow a Name Change");
       menu.add(changed_Name);

    exit = new JMenuItem("Exit");
    menu.add(exit);


    menu = new JMenu("Help");
    add(menu);

    menuItem = new JMenuItem("Help & Docs");
    //menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_F1, KeyEvent.CHAR_UNDEFINED) );
    menuItem.getAccessibleContext().setAccessibleDescription("Get Help or View Software documents");
    menu.add(menuItem);

    menuItem = new JMenuItem("About");
    menu.add(menuItem);

    MenuHandler menuHandler = new MenuHandler();
    menuItem.addActionListener(menuHandler);
    exit.addActionListener(menuHandler);


}


private class MenuHandler implements ActionListener{

    AgentName userName = new AgentName();

    @Override
    public void actionPerformed(ActionEvent e) throws UnsupportedOperationException {

            Object menuItem_Command = e.getActionCommand();

            if(menuItem_Command.equals("Change Name")){
                userName.setUserName(userName.getUserName());
            }
            else if(menuItem_Command.equals("Exit")){
                System.exit(0);
            }

    }

}
}

Answer 1

You never register the MenuHandler with the changed_name JMenuItem ...

Also, beware, you are reassigning menuItem multiple times, meaning hat only About is been registered with the MenuHandler

For example...

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setJMenuBar(new MenuBar());
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class MenuBar extends JMenuBar {

        // variable declaration
        private JMenu menu;
        private JMenuItem menuItem;
        private JMenuItem changed_Name;
        private JMenuItem exit;

        public MenuBar() {

            init();

        }

        private void init() {

            menu = new JMenu("File");
            add(menu);

            MenuHandler menuHandler = new MenuHandler();

            changed_Name = new JMenuItem("Change Name");
            changed_Name.setMnemonic(KeyEvent.VK_C);
            changed_Name.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_1, KeyEvent.ALT_MASK));
            changed_Name.getAccessibleContext().setAccessibleDescription("This Will Allow a Name Change");
            changed_Name.addActionListener(menuHandler);
            menu.add(changed_Name);

            exit = new JMenuItem("Exit");
            menu.add(exit);

            menu = new JMenu("Help");
            add(menu);

            menuItem = new JMenuItem("Help & Docs");
            //menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_F1, KeyEvent.CHAR_UNDEFINED) );
            menuItem.getAccessibleContext().setAccessibleDescription("Get Help or View Software documents");
            menuItem.addActionListener(menuHandler);
            menu.add(menuItem);

            menuItem = new JMenuItem("About");
            menuItem.addActionListener(menuHandler);
            menu.add(menuItem);

            exit.addActionListener(menuHandler);

        }

        private class MenuHandler implements ActionListener {

//          AgentName userName = new AgentName();

            @Override
            public void actionPerformed(ActionEvent e) throws UnsupportedOperationException {

                Object menuItem_Command = e.getActionCommand();

                System.out.println(menuItem_Command);

                if (menuItem_Command.equals("Change Name")) {
                    System.out.println("Yippe");
//                  userName.setUserName(userName.getUserName());
                } else if (menuItem_Command.equals("Exit")) {
                    System.exit(0);
                }

            }

        }
    }

    public class TestPane extends JPanel {

        public TestPane() {
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

    }
}

Generally speaking, you should really need to extend JMenuBar , but simply create an instance and add the menus you need to it

You may also consider having a look at How to Use Actions , which are self contained units, which contain their own configuration and action logic

For example...

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import static javax.swing.Action.ACCELERATOR_KEY;
import static javax.swing.Action.MNEMONIC_KEY;
import static javax.swing.Action.NAME;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setJMenuBar(new MenuBar());
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class ChangeNameAction extends AbstractAction {

        public ChangeNameAction() {
            putValue(ACCELERATOR_KEY, KeyStroke.getKeyStroke(KeyEvent.VK_1, KeyEvent.ALT_MASK));
            putValue(MNEMONIC_KEY, KeyEvent.VK_C);
            putValue(NAME, "Change Name");
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            System.out.println("Change name");
        }
    }

    public class ExitAction extends AbstractAction {

        public ExitAction() {
            putValue(ACCELERATOR_KEY, KeyStroke.getKeyStroke(KeyEvent.VK_4, KeyEvent.ALT_MASK));
            putValue(MNEMONIC_KEY, KeyEvent.VK_X);
            putValue(NAME, "Exit");
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            System.exit(0);
        }
    }

    public class HelpAction extends AbstractAction {

        public HelpAction() {
            putValue(ACCELERATOR_KEY, KeyStroke.getKeyStroke(KeyEvent.VK_F1, 0));
            putValue(MNEMONIC_KEY, KeyEvent.VK_H);
            putValue(NAME, "Help & Docs");
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            System.out.println("Help and docs");
        }
    }

    public class AboutAction extends AbstractAction {

        public AboutAction() {
            putValue(NAME, "About");
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            System.out.println("About");
        }
    }

    public class MenuBar extends JMenuBar {

        // variable declaration
        private JMenu menu;
        private JMenuItem menuItem;
        private JMenuItem changed_Name;
        private JMenuItem exit;

        public MenuBar() {

            init();

        }

        private void init() {

            menu = new JMenu("File");
            add(menu);

            menu.add(new ChangeNameAction());
            menu.add(new ExitAction());

            menu = new JMenu("Help");
            add(menu);

            menu.add(new HelpAction());
            menu.add(new AboutAction());

        }

        private class MenuHandler implements ActionListener {

    //          AgentName userName = new AgentName();
            @Override
            public void actionPerformed(ActionEvent e) throws UnsupportedOperationException {

                Object menuItem_Command = e.getActionCommand();

                System.out.println(menuItem_Command);

                if (menuItem_Command.equals("Change Name")) {
                    System.out.println("Yippe");
                    //                  userName.setUserName(userName.getUserName());
                } else if (menuItem_Command.equals("Exit")) {
                    System.exit(0);
                }

            }

        }
    }

    public class TestPane extends JPanel {

        public TestPane() {
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

    }
}

Answer 2

It is probably working, but you do not get feedback because you are changing the name to the previous one. If you put some other value in the setUserName method you will see