import javax.swing.AbstractButton;import javax.swing.JButton;import javax.swing.JPanel;import javax.swing.JFrame;import javax.swing.ImageIcon;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.KeyEvent;/*  * ButtonDemo.java requires the following files: *   images/right.gif *   images/middle.gif *   images/left.gif */public class ButtonDemo extends JPanel                        implements ActionListener {    protected JButton b1, b2, b3;    public ButtonDemo() {        ImageIcon leftButtonIcon = createImageIcon("images/right.gif");        ImageIcon middleButtonIcon = createImageIcon("images/middle.gif");        ImageIcon rightButtonIcon = createImageIcon("images/left.gif");        b1 = new JButton("Disable middle button", leftButtonIcon);        b1.setVerticalTextPosition(AbstractButton.CENTER);        b1.setHorizontalTextPosition(AbstractButton.LEADING); //aka LEFT, for left-to-right locales        b1.setMnemonic(KeyEvent.VK_D);        b1.setActionCommand("disable");        b2 = new JButton("Middle button", middleButtonIcon);        b2.setVerticalTextPosition(AbstractButton.BOTTOM);        b2.setHorizontalTextPosition(AbstractButton.CENTER);        b2.setMnemonic(KeyEvent.VK_M);        b3 = new JButton("Enable middle button", rightButtonIcon);        //Use the default text position of CENTER, TRAILING (RIGHT).        b3.setMnemonic(KeyEvent.VK_E);        b3.setActionCommand("enable");        b3.setEnabled(false);        //Listen for actions on buttons 1 and 3.        b1.addActionListener(this);        b3.addActionListener(this);        b1.setToolTipText("Click this button to disable the middle button.");        b2.setToolTipText("This middle button does nothing when you click it.");        b3.setToolTipText("Click this button to enable the middle button.");        //Add Components to this container, using the default FlowLayout.        add(b1);        add(b2);        add(b3);    }    public void actionPerformed(ActionEvent e) {        if ("disable".equals(e.getActionCommand())) {            b2.setEnabled(false);            b1.setEnabled(false);            b3.setEnabled(true);        } else {            b2.setEnabled(true);            b1.setEnabled(true);            b3.setEnabled(false);        }    }    /** Returns an ImageIcon, or null if the path was invalid. */    protected static ImageIcon createImageIcon(String path) {        java.net.URL imgURL = ButtonDemo.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() {        //Create and set up the window.        JFrame frame = new JFrame("ButtonDemo");        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        //Create and set up the content pane.        ButtonDemo newContentPane = new ButtonDemo();        newContentPane.setOpaque(true); //content panes must be opaque        frame.setContentPane(newContentPane);        //Display the window.        frame.pack();        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();             }        });    }}