Track focus with KeyboardFocusManager

Description

Demo Code

/*/*from w w  w  . j a v  a2 s. com*/
 * TrackFocusDemo.java requires the following files:
 *     Picture.java
 *     images/Maya.jpg
 *     images/Anya.jpg
 *     images/Laine.jpg
 *     images/Cosmo.jpg
 *     images/Adele.jpg
 *     images/Alexi.jpg
 */
import javax.swing.*;

import java.beans.*; //Property change stuff
import java.awt.*;
import java.awt.event.*;

import javax.swing.InputMap;
import javax.swing.KeyStroke;
import javax.swing.Action;
import javax.swing.JComponent;
import javax.accessibility.Accessible;

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

class Picture extends JComponent implements MouseListener, FocusListener,
        Accessible {
    Image image;

    public Picture(Image image) {

        this.image = image;
        setFocusable(true);
        addMouseListener(this);
        addFocusListener(this);
    }

    public void mouseClicked(MouseEvent e) {
        //Since the user clicked on us, let's get focus!
        requestFocusInWindow();
    }

    public void mouseEntered(MouseEvent e) {
    }

    public void mouseExited(MouseEvent e) {
    }

    public void mousePressed(MouseEvent e) {
    }

    public void mouseReleased(MouseEvent e) {
    }

    public void focusGained(FocusEvent e) {
        //Draw the component with a red border
        //indicating that it has focus.
        this.repaint();
    }

    public void focusLost(FocusEvent e) {
        //Draw the component with a black border
        //indicating that it doesn't have focus.
        this.repaint();
    }

    protected void paintComponent(Graphics graphics) {
        Graphics g = graphics.create();

        //Draw in our entire space, even if isOpaque is false.
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, image == null ? 125 : image.getWidth(this),
                image == null ? 125 : image.getHeight(this));

        if (image != null) {
            //Draw image at its natural size of 125x125.
            g.drawImage(image, 0, 0, this);
        }

        //Add a border, red if picture currently has focus
        if (isFocusOwner()) {
            g.setColor(Color.RED);
        } else {
            g.setColor(Color.BLACK);
        }
        g.drawRect(0, 0, image == null ? 125 : image.getWidth(this),
                image == null ? 125 : image.getHeight(this));
        g.dispose();
    }
}


public class TrackFocusDemo extends JPanel {

    Picture pic1, pic2, pic3, pic4, pic5, pic6;
    JLabel info;
    static String mayaString = "Maya";
    static String anyaString = "Anya";
    static String laineString = "Laine";
    static String cosmoString = "Cosmo";
    static String adeleString = "Adele";
    static String alexiString = "Alexi";
    String[] comments = { "Oops. What is this?", "This is Maya",
            "This is Anya", "This is Laine", "This is Cosmo",
            "This is Adele", "This is Alexi" };

    public TrackFocusDemo() {
        super(new BorderLayout());

        JPanel mugshots = new JPanel(new GridLayout(2, 3));
        pic1 = new Picture(createImageIcon("images/" + mayaString + ".jpg",
                mayaString).getImage());
        pic1.setName("1");
        mugshots.add(pic1);
        pic2 = new Picture(createImageIcon("images/" + anyaString + ".jpg",
                anyaString).getImage());
        pic2.setName("2");
        mugshots.add(pic2);
        pic3 = new Picture(createImageIcon(
                "images/" + laineString + ".jpg", laineString).getImage());
        pic3.setName("3");
        mugshots.add(pic3);
        pic4 = new Picture(createImageIcon(
                "images/" + cosmoString + ".jpg", cosmoString).getImage());
        pic4.setName("4");
        mugshots.add(pic4);
        pic5 = new Picture(createImageIcon(
                "images/" + adeleString + ".jpg", adeleString).getImage());
        pic5.setName("5");
        mugshots.add(pic5);
        pic6 = new Picture(createImageIcon(
                "images/" + alexiString + ".jpg", alexiString).getImage());
        pic6.setName("6");
        mugshots.add(pic6);

        info = new JLabel("Nothing selected");

        setPreferredSize(new Dimension(450, 350));
        add(mugshots, BorderLayout.CENTER);
        add(info, BorderLayout.PAGE_END);
        setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));

        KeyboardFocusManager focusManager = KeyboardFocusManager
                .getCurrentKeyboardFocusManager();
        focusManager
                .addPropertyChangeListener(new PropertyChangeListener() {
                    public void propertyChange(PropertyChangeEvent e) {
                        String prop = e.getPropertyName();
                        if (("focusOwner".equals(prop))
                                && ((e.getNewValue()) instanceof Picture)) {

                            Component comp = (Component) e.getNewValue();
                            String name = comp.getName();
                            Integer num = new Integer(name);
                            int index = num.intValue();
                            if (index < 0 || index > comments.length) {
                                index = 0;
                            }
                            info.setText(comments[index]);
                        }
                    }
                });
    }

    /** Returns an ImageIcon, or null if the path was invalid. */
    protected static ImageIcon createImageIcon(String path,
            String description) {
        java.net.URL imageURL = TrackFocusDemo.class.getResource(path);

        if (imageURL == null) {
            System.err.println("Resource not found: " + path);
            return null;
        } else {
            return new ImageIcon(imageURL, description);
        }
    }

    /**
     * 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("TrackFocusDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JComponent newContentPane = new TrackFocusDemo();
        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) {
        /* Use an appropriate Look and Feel */
        try {
            //UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
            //UIManager.setLookAndFeel("com.sun.java.swing.plaf.gtk.GTKLookAndFeel");
            UIManager
                    .setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
        } catch (UnsupportedLookAndFeelException ex) {
            ex.printStackTrace();
        } catch (IllegalAccessException ex) {
            ex.printStackTrace();
        } catch (InstantiationException ex) {
            ex.printStackTrace();
        } catch (ClassNotFoundException ex) {
            ex.printStackTrace();
        }
        /* Turn off metal's use of bold fonts */
        UIManager.put("swing.boldMetal", Boolean.FALSE);

        //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();
            }
        });
    }
}

/*
 * Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
Track focus with KeyboardFocusManager - Java Swing

Description

Demo Code

Related Tutorials
