Swing JMenuBar類

JMenuBar類提供選單欄的實現。

類宣告

以下是javax.swing.JMenuBar類的宣告 -

public class JMenuBar
   extends JComponent
      implements Accessible, MenuElement

類建構函式

類方法

以下是Swing JMenuBar類中的方法列表。

• 參閱：https://docs.oracle.com/javase/8/docs/api/javax/swing/JMenuBar.html

方法繼承

該類繼承以下類中的方法 -

• javax.swing.JComponent
• java.awt.Container
• java.awt.Component
• java.lang.Object

JMenuBar範例

使用編輯器建立以下Java程式：JMenuBarDemo.java

package com.yiibai.menu;

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

public class JMenuBarDemo {
    private JFrame mainFrame;
    private JLabel headerLabel;
    private JLabel statusLabel;
    private JPanel controlPanel;

    public JMenuBarDemo() {
        prepareGUI();
    }

    public static void main(String[] args) {
        JMenuBarDemo swingMenuDemo = new JMenuBarDemo();
        swingMenuDemo.showMenuDemo();
    }

    private void prepareGUI() {
        mainFrame = new JFrame("Java SWING JMenuBar範例(tw511.com)");
        mainFrame.setSize(400, 400);
        mainFrame.setLayout(new GridLayout(3, 1));

        headerLabel = new JLabel("", JLabel.CENTER);
        statusLabel = new JLabel("", JLabel.CENTER);
        statusLabel.setSize(350, 100);

        mainFrame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent windowEvent) {
                System.exit(0);
            }
        });
        controlPanel = new JPanel();
        controlPanel.setLayout(new FlowLayout());

        mainFrame.add(headerLabel);
        mainFrame.add(controlPanel);
        mainFrame.add(statusLabel);
        mainFrame.setVisible(true);
    }

    private void showMenuDemo() {
        // create a menu bar
        final JMenuBar menuBar = new JMenuBar();

        // create menus
        JMenu fileMenu = new JMenu("檔案");
        JMenu editMenu = new JMenu("編輯");
        final JMenu aboutMenu = new JMenu("關於");
        final JMenu linkMenu = new JMenu("連結");

        // create menu items
        JMenuItem newMenuItem = new JMenuItem("新建");
        newMenuItem.setMnemonic(KeyEvent.VK_N);
        newMenuItem.setActionCommand("New");

        JMenuItem openMenuItem = new JMenuItem("開啟");
        openMenuItem.setActionCommand("Open");

        JMenuItem saveMenuItem = new JMenuItem("儲存");
        saveMenuItem.setActionCommand("Save");

        JMenuItem exitMenuItem = new JMenuItem("退出");
        exitMenuItem.setActionCommand("Exit");

        JMenuItem cutMenuItem = new JMenuItem("剪下");
        cutMenuItem.setActionCommand("Cut");

        JMenuItem copyMenuItem = new JMenuItem("複製");
        copyMenuItem.setActionCommand("Copy");

        JMenuItem pasteMenuItem = new JMenuItem("貼上");
        pasteMenuItem.setActionCommand("Paste");

        MenuItemListener menuItemListener = new MenuItemListener();

        newMenuItem.addActionListener(menuItemListener);
        openMenuItem.addActionListener(menuItemListener);
        saveMenuItem.addActionListener(menuItemListener);
        exitMenuItem.addActionListener(menuItemListener);
        cutMenuItem.addActionListener(menuItemListener);
        copyMenuItem.addActionListener(menuItemListener);
        pasteMenuItem.addActionListener(menuItemListener);

        final JCheckBoxMenuItem showWindowMenu = new JCheckBoxMenuItem("顯示關於", true);
        showWindowMenu.addItemListener(new ItemListener() {
            public void itemStateChanged(ItemEvent e) {

                if (showWindowMenu.getState()) {
                    menuBar.add(aboutMenu);
                } else {
                    menuBar.remove(aboutMenu);
                }
            }
        });
        final JRadioButtonMenuItem showLinksMenu = new JRadioButtonMenuItem("顯示連結", true);
        showLinksMenu.addItemListener(new ItemListener() {
            public void itemStateChanged(ItemEvent e) {

                if (menuBar.getMenu(3) != null) {
                    menuBar.remove(linkMenu);
                    mainFrame.repaint();
                } else {
                    menuBar.add(linkMenu);
                    mainFrame.repaint();
                }
            }
        });
        // add menu items to menus
        fileMenu.add(newMenuItem);
        fileMenu.add(openMenuItem);
        fileMenu.add(saveMenuItem);
        fileMenu.addSeparator();
        fileMenu.add(showWindowMenu);
        fileMenu.addSeparator();
        fileMenu.add(showLinksMenu);
        fileMenu.addSeparator();
        fileMenu.add(exitMenuItem);

        editMenu.add(cutMenuItem);
        editMenu.add(copyMenuItem);
        editMenu.add(pasteMenuItem);

        // add menu to menubar
        menuBar.add(fileMenu);
        menuBar.add(editMenu);
        menuBar.add(aboutMenu);
        menuBar.add(linkMenu);

        // add menubar to the frame
        mainFrame.setJMenuBar(menuBar);
        mainFrame.setVisible(true);
    }

    class MenuItemListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            statusLabel.setText(e.getActionCommand() + " JMenuItem clicked.");
        }
    }
}

執行上面範例程式碼，得到以下結果：