import java.awt.*;import java.awt.event.*;import javax.swing.JMenu;import javax.swing.JMenuItem;import javax.swing.JCheckBoxMenuItem;import javax.swing.JRadioButtonMenuItem;import javax.swing.ButtonGroup;import javax.swing.JMenuBar;import javax.swing.KeyStroke;import javax.swing.ImageIcon;import javax.swing.JPanel;import javax.swing.JTextArea;import javax.swing.JScrollPane;import javax.swing.JFrame;/* MenuDemo.java is a 1.4 application that requires images/middle.gif. *//* * This class is just like MenuLookDemo, except the menu items * actually do something, thanks to event listeners. */public class MenuDemo implements ActionListener, ItemListener {    JTextArea output;    JScrollPane scrollPane;    String newline = "\n";    public JMenuBar createMenuBar() {        JMenuBar menuBar;        JMenu menu, submenu;        JMenuItem menuItem;        JRadioButtonMenuItem rbMenuItem;        JCheckBoxMenuItem cbMenuItem;        //Create the menu bar.        menuBar = new JMenuBar();        //Build the first menu.        menu = new JMenu("A Menu");        menu.setMnemonic(KeyEvent.VK_A);        menu.getAccessibleContext().setAccessibleDescription(                "The only menu in this program that has menu items");        menuBar.add(menu);        //a group of JMenuItems        menuItem = new JMenuItem("A text-only menu item",                                 KeyEvent.VK_T);        //menuItem.setMnemonic(KeyEvent.VK_T); //used constructor instead        menuItem.setAccelerator(KeyStroke.getKeyStroke(                KeyEvent.VK_1, ActionEvent.ALT_MASK));        menuItem.getAccessibleContext().setAccessibleDescription(                "This doesn't really do anything");        menuItem.addActionListener(this);        menu.add(menuItem);        ImageIcon icon = createImageIcon("images/middle.gif");        menuItem = new JMenuItem("Both text and icon", icon);        menuItem.setMnemonic(KeyEvent.VK_B);        menuItem.addActionListener(this);        menu.add(menuItem);        menuItem = new JMenuItem(icon);        menuItem.setMnemonic(KeyEvent.VK_D);        menuItem.addActionListener(this);        menu.add(menuItem);        //a group of radio button menu items        menu.addSeparator();        ButtonGroup group = new ButtonGroup();        rbMenuItem = new JRadioButtonMenuItem("A radio button menu item");        rbMenuItem.setSelected(true);        rbMenuItem.setMnemonic(KeyEvent.VK_R);        group.add(rbMenuItem);        rbMenuItem.addActionListener(this);        menu.add(rbMenuItem);        rbMenuItem = new JRadioButtonMenuItem("Another one");        rbMenuItem.setMnemonic(KeyEvent.VK_O);        group.add(rbMenuItem);        rbMenuItem.addActionListener(this);        menu.add(rbMenuItem);        //a group of check box menu items        menu.addSeparator();        cbMenuItem = new JCheckBoxMenuItem("A check box menu item");        cbMenuItem.setMnemonic(KeyEvent.VK_C);        cbMenuItem.addItemListener(this);        menu.add(cbMenuItem);        cbMenuItem = new JCheckBoxMenuItem("Another one");        cbMenuItem.setMnemonic(KeyEvent.VK_H);        cbMenuItem.addItemListener(this);        menu.add(cbMenuItem);        //a submenu        menu.addSeparator();        submenu = new JMenu("A submenu");        submenu.setMnemonic(KeyEvent.VK_S);        menuItem = new JMenuItem("An item in the submenu");        menuItem.setAccelerator(KeyStroke.getKeyStroke(                KeyEvent.VK_2, ActionEvent.ALT_MASK));        menuItem.addActionListener(this);        submenu.add(menuItem);        menuItem = new JMenuItem("Another item");        menuItem.addActionListener(this);        submenu.add(menuItem);        menu.add(submenu);        //Build second menu in the menu bar.        menu = new JMenu("Another Menu");        menu.setMnemonic(KeyEvent.VK_N);        menu.getAccessibleContext().setAccessibleDescription(                "This menu does nothing");        menuBar.add(menu);        return menuBar;    }    public Container createContentPane() {        //Create the content-pane-to-be.        JPanel contentPane = new JPanel(new BorderLayout());        contentPane.setOpaque(true);        //Create a scrolled text area.        output = new JTextArea(5, 30);        output.setEditable(false);        scrollPane = new JScrollPane(output);        //Add the text area to the content pane.        contentPane.add(scrollPane, BorderLayout.CENTER);        return contentPane;    }    public void actionPerformed(ActionEvent e) {        JMenuItem source = (JMenuItem)(e.getSource());        String s = "Action event detected."                   + newline                   + "    Event source: " + source.getText()                   + " (an instance of " + getClassName(source) + ")";        output.append(s + newline);        output.setCaretPosition(output.getDocument().getLength());    }    public void itemStateChanged(ItemEvent e) {        JMenuItem source = (JMenuItem)(e.getSource());        String s = "Item event detected."                   + newline                   + "    Event source: " + source.getText()                   + " (an instance of " + getClassName(source) + ")"                   + newline                   + "    New state: "                   + ((e.getStateChange() == ItemEvent.SELECTED) ?                     "selected":"unselected");        output.append(s + newline);        output.setCaretPosition(output.getDocument().getLength());    }    // Returns just the class name -- no package info.    protected String getClassName(Object o) {        String classString = o.getClass().getName();        int dotIndex = classString.lastIndexOf(".");        return classString.substring(dotIndex+1);    }    /** Returns an ImageIcon, or null if the path was invalid. */    protected static ImageIcon createImageIcon(String path) {        java.net.URL imgURL = MenuDemo.class.getResource(path);        if (imgURL != null) {            return new ImageIcon(imgURL);        } else {            System.err.println("Couldn't find file: " + path);            return null;        }    }    /**     * Create the GUI and show it.  For thread safety,     * this method should be invoked from the     * event-dispatching thread.     */    private static void createAndShowGUI() {        //Make sure we have nice window decorations.        JFrame.setDefaultLookAndFeelDecorated(true);        //Create and set up the window.        JFrame frame = new JFrame("MenuDemo");        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        //Create and set up the content pane.        MenuDemo demo = new MenuDemo();        frame.setJMenuBar(demo.createMenuBar());        frame.setContentPane(demo.createContentPane());        //Display the window.        frame.setSize(450, 260);        frame.setVisible(true);    }    public static void main(String[] args) {        //Schedule a job for the event-dispatching thread:        //creating and showing this application's GUI.        javax.swing.SwingUtilities.invokeLater(new Runnable() {            public void run() {                createAndShowGUI();            }        });    }}