Question

如何在单击时检索当前选定的菜单或菜单项，并在控制台上打印后续路径。在这段代码中，我完成了最多4级的菜单和子菜单。并且想要在单击时打印所选菜单和子菜单的路径。我正在为这个程序使用swing概念。请帮忙。提前谢谢。

import java.awt.Component;
import java.awt.event.KeyEvent;

import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.MenuElement;
import javax.swing.MenuSelectionManager;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class Menu {

  public static void main(final String args[]) {
    JFrame frame = new JFrame("MenuSample Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JMenuBar menuBar = new JMenuBar();

JMenu worldMenu = new JMenu("world");
menuBar.add(worldMenu);


JMenu indMenu = new JMenu("India");
worldMenu.add(indMenu);
/* creates menu */
JMenu odMenu = new JMenu("Odisha");
indMenu.add(odMenu);

JMenu delhiMenu = new JMenu("Delhi");
indMenu.add(delhiMenu);

JMenu upMenu = new JMenu("Uttar Pradesh");
indMenu.add(upMenu);

JMenu mpMenu = new JMenu("Madhya Pradesh");
    indMenu.add(mpMenu);

    JMenu ausMenu = new JMenu("Australia");
worldMenu.add(ausMenu);

JMenu AmericaMenu = new JMenu("America");
worldMenu.add(AmericaMenu);

/* creates submenu */
JMenu bbMenu = new JMenu("Bhubaneswar");
odMenu.add(bbMenu);

JMenu bmMenu = new JMenu("Berhampur");
odMenu.add(bmMenu);
/*creates sub sub menu */
JMenuItem rjMenuItem = new JMenuItem("Raj Mahal");
bbMenu.add(rjMenuItem);

JMenuItem abMenuItem = new JMenuItem("Acharya Bihar");
bbMenu.add(abMenuItem);

JMenuItem bnMenuItem = new JMenuItem("Bani Bihar");
bbMenu.add(bnMenuItem);
/* retrieving path */

MenuSelectionManager.defaultManager().addChangeListener(
        new ChangeListener() {
          public void stateChanged(ChangeEvent evt) {

            MenuElement[] path = MenuSelectionManager.defaultManager()
                .getSelectedPath();

            //
            int s=0;

            for (int i = 0; i < path.length; i++) {
                Component c = path[i].getComponent();
                if (c instanceof JMenuItem) {
                JMenuItem mi = (JMenuItem) c;
                String label = mi.getText();
                System.out.println("LEVEL----" + s);
                System.out.println("you hv selected:"+label);
                s++;


              }
            }

          }
        });

    //

    frame.setJMenuBar(menuBar);
    frame.setSize(350, 250);
    frame.setVisible(true);
  }
}

Answer 1

如何获取当前选择的

菜单 - 无法选择父级JMenu。你为什么想知道如果鼠标结束了吗？
MenuItem - 接受Action界面

不使用Action interface这是一个非常普遍的疏忽。当使用Swing开发使动作成为你的朋友时，它会很好地对待你。你使用MenuSelectionManager走错了路。

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

public class MenuExample {
    private JFrame frame;
    private JLabel choiceIndicator;

    MenuExample create() {
        frame = createFrame();
        choiceIndicator = new JLabel();
        frame.setJMenuBar(createMenuBar());
        frame.getContentPane().add(createContent());

        return this;
    }

    private Component createContent() {
        JPanel panel = new JPanel();

        panel.add(new JLabel("Last menu item choice:"));
        panel.add(choiceIndicator);

        return panel;
    }

    private JMenuBar createMenuBar() {
        JMenuBar menuBar = new JMenuBar();
        menuBar.add(createWorld());
        return menuBar;
    }

    private JMenu createWorld() {
        JMenu worldMenu = new JMenu("World");

        worldMenu.add(createIndia());
        worldMenu.add(new JMenu("Australia"));
        worldMenu.add(new JMenu("America"));

        return worldMenu;
    }

    private JMenu createIndia() {
        JMenu india = new JMenu("India");

        india.add(createOdisha());
        india.add(new JMenu("Delhi"));
        india.add(new JMenu("Uttar Pradesh"));
        india.add(new JMenu("Madhya Pradesh"));

        return india;
    }

    private JMenuItem createOdisha() {
        JMenu menu = new JMenu("Odisha");

        menu.add(createBhubaneswar());
        menu.add(new JMenu("Berhampur"));

        return menu;
    }

    private JMenuItem createBhubaneswar() {
        JMenu menu = new JMenu("Bhubaneswar");
        menu.add(choiceItem("Raj Mahal"));
        menu.add(choiceItem("Acharya Bihar"));
        menu.add(choiceItem("Bani Bihar"));

        return menu;
    }

    private JMenuItem choiceItem(String text) {
        return new JMenuItem(new Choice(text, choiceIndicator));
    }

    private JFrame createFrame() {
        JFrame frame = new JFrame(getClass().getSimpleName());
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        return frame;
    }

    void show() {
        frame.setSize(350, 250);
        frame.setResizable(false);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new MenuExample().create().show();
            }
        });
    }

    class Choice extends AbstractAction {
        private final JLabel choiceIndicator;

        public Choice(String text, JLabel choiceIndicator) {
            this(text, null, null, null, choiceIndicator);
        }

        public Choice(String text, ImageIcon icon, String desc, Integer mnemonic, JLabel choiceIndicator) {
            super(text, icon);
            putValue(SHORT_DESCRIPTION, desc);
            putValue(MNEMONIC_KEY, mnemonic);

            this.choiceIndicator = choiceIndicator;
        }

        public void actionPerformed(ActionEvent e) {
            choiceIndicator.setText(e.getActionCommand());
        }
    }
}

如何获取当前选定的Menu或MenuItem

1 个答案: