AWT » AWT MenuBar類

AWT MenuBar類

MenuBar類系結到框架提供了選單欄，並且因平台而異。

類的宣告

以下是宣告的java.awt.MenuBar類：

public class MenuBar
   extends MenuComponent
      implements MenuContainer, Accessible

類別建構函式

S.N. 建構函式與說明
1 MenuBar() 
Creates a new menu bar.

類方法

S.N. 方法及說明
1 void dispatchEvent(AWTEvent e) 
2 Menu add(Menu m) 
Adds the specified menu to the menu bar.
3 void addNotify() 
Creates the menu bar's peer.
4 int countMenus() 
Deprecated. As of JDK version 1.1, replaced by getMenuCount().
5 void deleteShortcut(MenuShortcut s) 
Deletes the specified menu shortcut.
6 AccessibleContext getAccessibleContext() 
Gets the AccessibleContext associated with this MenuBar.
7 Menu getHelpMenu() 
Gets the help menu on the menu bar.
8 Menu getMenu(int i) 
Gets the specified menu.
9 int getMenuCount() 
Gets the number of menus on the menu bar.
10 MenuItem getShortcutMenuItem(MenuShortcut s) 
Gets the instance of MenuItem associated with the specified MenuShortcut object, or null if none of the menu items being managed by this menu bar is associated with the specified menu shortcut.
11 void remove(int index) 
Removes the menu located at the specified index from this menu bar.
12 void remove(MenuComponent m) 
Removes the specified menu component from this menu bar.
13 void removeNotify() 
Removes the menu bar's peer.
14 void setHelpMenu(Menu m) 
Sets the specified menu to be this menu bar's help menu.
15 Enumeration shortcuts() 
Gets an enumeration of all menu shortcuts this menu bar is managing.

繼承的方法

這個類繼承的方法從以下類別：

  • java.awt.MenuComponent

  • java.lang.Object

MenuBar 範例

在選擇使用任何編輯器建立以下java程式 D:/ > AWT > com > yiibai > gui >

AWTMenuDemo 
package com.yiibai.gui;

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

public class AWTMenuDemo {
   private Frame mainFrame;
   private Label headerLabel;
   private Label statusLabel;
   private Panel controlPanel;

   public AWTMenuDemo(){
      prepareGUI();
   }

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

   private void prepareGUI(){
      mainFrame = new Frame("Java AWT Examples");
      mainFrame.setSize(400,400);
      mainFrame.setLayout(new GridLayout(3, 1));
      mainFrame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }        
      });    
      headerLabel = new Label();
      headerLabel.setAlignment(Label.CENTER);
      statusLabel = new Label();        
      statusLabel.setAlignment(Label.CENTER);
      statusLabel.setSize(350,100);

      controlPanel = new Panel();
      controlPanel.setLayout(new FlowLayout());

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

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

      //create menus
      Menu fileMenu = new Menu("File");
      Menu editMenu = new Menu("Edit"); 
      final Menu aboutMenu = new Menu("About");

      //create menu items
      MenuItem newMenuItem = 
         new MenuItem("New",new MenuShortcut(KeyEvent.VK_N));
      newMenuItem.setActionCommand("New");

      MenuItem openMenuItem = new MenuItem("Open");
      openMenuItem.setActionCommand("Open");

      MenuItem saveMenuItem = new MenuItem("Save");
      saveMenuItem.setActionCommand("Save");

      MenuItem exitMenuItem = new MenuItem("Exit");
      exitMenuItem.setActionCommand("Exit");

      MenuItem cutMenuItem = new MenuItem("Cut");
      cutMenuItem.setActionCommand("Cut");

      MenuItem copyMenuItem = new MenuItem("Copy");
      copyMenuItem.setActionCommand("Copy");

      MenuItem pasteMenuItem = new MenuItem("Paste");
      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 CheckboxMenuItem showWindowMenu = 
         new CheckboxMenuItem("Show About", true);
      showWindowMenu.addItemListener(new ItemListener() {
         public void itemStateChanged(ItemEvent e) {
            if(showWindowMenu.getState()){
               menuBar.add(aboutMenu);
            }else{
               menuBar.remove(aboutMenu);
            }
         }
      });

   //add menu items to menus
   fileMenu.add(newMenuItem);
   fileMenu.add(openMenuItem);
   fileMenu.add(saveMenuItem);
   fileMenu.addSeparator();
   fileMenu.add(showWindowMenu);
   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);

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

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

編譯程式，使用命令提示字元。進入到D:/> AWT，然後鍵入以下命令。

D:AWT>javac comyiibaiguiAWTMenuDemo.java

如果沒有錯誤出現，這意味著編譯成功。使用下面的命令來執行程式。

D:AWT>java com.yiibai.gui.AWTMenuDemo

驗證下面的輸出

AWT MenuBar