在Java中，设定窗口标题可以简单的调用JFrame所提供的setTitle()方法，该方法接受一个字符串作为窗口的新标题。创建一个下拉式菜单则涉及到创建一个菜单条JMenuBar，创建一个菜单JMenu，以及创建一个菜单项JMenuItem等操作。在下面的程序片断中详细展示了创建一个下拉式菜单的整个过程，其中菜单项的消息处理部分addActionListener()和setActionCommand() 是使得菜单能够正常工作的关键。F_New.addActionListener(this)方法指定程序使用NotePad类所提供的消息处理方法actionPerformed()来处理这个动作，F_New.setActionCommand("F_New")方法则指定程序在用户选取该菜单项的时候向系统发送一个参数为"F_New" 的菜单动作消息，这个消息最后将由NotePad类中的actionPerformed()方法来处理。// 创建下拉式菜单
private JMenuBar CreateMenu()
{
// 创建一个菜单条
JMenuBar EditorMenu = new JMenuBar();
// 创建一个File菜单
JMenu FileMenu = new JMenu("File"); // 创建一个菜单项
JMenuItem F_New = new JMenuItem("New");
// 添加菜单消息处理
F_New.addActionListener(this);
F_New.setActionCommand("F_New");
// 将该裁单项添加到菜单中
FileMenu.add(F_New); // 将File菜单添加到菜单条
EditorMenu.add(FileMenu);
// 返回菜单条
return EditorMenu;
}
private JMenuBar CreateMenu()
{
// 创建一个菜单条
JMenuBar EditorMenu = new JMenuBar();
// 创建一个File菜单
JMenu FileMenu = new JMenu("File"); // 创建一个菜单项
JMenuItem F_New = new JMenuItem("New");
// 添加菜单消息处理
F_New.addActionListener(this);
F_New.setActionCommand("F_New");
// 将该裁单项添加到菜单中
FileMenu.add(F_New); // 将File菜单添加到菜单条
EditorMenu.add(FileMenu);
// 返回菜单条
return EditorMenu;
}
import java.awt.*;import java.awt.event.*;import javax.swing.*;public class MenuBarExample extends JPanel implements ItemListener{ static JFrame myFrame; Font myFont = new Font("Dialog", Font.PLAIN, 16); public MenuBarExample(){ setFont(myFont); JTabbedPane tabs = new JTabbedPane(SwingConstants.BOTTOM); Icon icon = new ImageIcon ("feet.gif"); JButton button = new JButton(icon); JLabel label = new JLabel ("Hello World!"); tabs.addTab("Hello World",label); tabs.addTab("Feet",icon,button); setLayout(new BorderLayout()); add(tabs,"Center"); add(createMenu(),"North"); } public JMenuBar createMenu(){ JMenuBar menuBar = new JMenuBar(); // File Menu - create this so we have at least two menu options JMenu file = (JMenu) menuBar.add(new JMenu("File")); file.setMnemonic('F'); JMenuItem mi; //Temporary place holder //Add several items under 'File' these won't do anything. mi = (JMenuItem) file.add(new JMenuItem("Open")); mi.setMnemonic('O'); mi = (JMenuItem) file.add(new JMenuItem("Save")); mi.setMnemonic('S'); mi = (JMenuItem) file.add(new JMenuItem("Save As...")); mi.setMnemonic('A'); file.add(new JSeparator()); mi = (JMenuItem) file.add(new JMenuItem("Exit")); // Look and Feel Menu JMenu options = (JMenu) menuBar.add(new JMenu("L&F")); options.setMnemonic('L'); // Look and Feel Radio control ButtonGroup group = new ButtonGroup(); mi = options.add(new JCheckBoxMenuItem("Windows L&F")); mi.setActionCommand("com.sun.java.swing.plaf.windows.WindowsLookAndFeel"); //If the current look and feel is windows, select this item. mi.setSelected(UIManager.getLookAndFeel().getName().equals("Windows")); //group.add(mi); mi.addItemListener(this); // mi.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_1, ActionEvent.ALT_MASK)); mi = options.add(new JRadioButtonMenuItem("Motif L&F")); mi.setActionCommand("com.sun.java.swing.plaf.motif.MotifLookAndFeel"); mi.setSelected(UIManager.getLookAndFeel().getName().equals("CDE/Motif")); group.add(mi); mi.addItemListener(this); // mi.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_2, ActionEvent.ALT_MASK)); mi = options.add(new JRadioButtonMenuItem("Metal L&F")); mi.setActionCommand("javax.swing.plaf.metal.MetalLookAndFeel"); mi.setSelected(UIManager.getLookAndFeel().getName().equals("Metal")); // metalMenuItem.setSelected(true); group.add(mi); mi.addItemListener(this); // metalMenuItem.setAccelerator(KeyStroke.getKeyStroke (KeyEvent.VK_3, ActionEvent.ALT_MASK)); return menuBar; } public void itemStateChanged(ItemEvent e) { Component root = myFrame; //Bump the cursor into a wait mode while we make this change root.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR)); //Get the source of the event. JRadioButtonMenuItem button = (JRadioButtonMenuItem) e.getSource(); try { if(button.isSelected()) { UIManager.setLookAndFeel(button.getActionCommand()); button.setEnabled(true); SwingUtilities.updateComponentTreeUI(myFrame); } } catch (UnsupportedLookAndFeelException exc) { // Error - unsupported L&F button.setEnabled(false); System.err.println("Unsupported LookAndFeel: " + button.getText()); }catch (Exception exc2){ System.err.println("Couldn't load Look and feel" + button.getText()); } root.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR)); } public static void main(String args[]){ myFrame = new JFrame("MenuBar Example"); MenuBarExample menuExample = new MenuBarExample(); myFrame.getContentPane().add("Center",menuExample); myFrame.setSize(400,200); myFrame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) {System.exit(0);} }); myFrame.setVisible(true); }}