    001    /* ========================================================================
    002     * JCommon : a free general purpose class library for the Java(tm) platform
    003     * ========================================================================
    004     *
    005     * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
    006     *
    007     * Project Info:  http://www.jfree.org/jcommon/index.html
    008     *
    009     * This library is free software; you can redistribute it and/or modify it
    010     * under the terms of the GNU Lesser General Public License as published by
    011     * the Free Software Foundation; either version 2.1 of the License, or
    012     * (at your option) any later version.
    013     *
    014     * This library is distributed in the hope that it will be useful, but
    015     * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    016     * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
    017     * License for more details.
    018     *
    019     * You should have received a copy of the GNU Lesser General Public
    020     * License along with this library; if not, write to the Free Software
    021     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
    022     * USA.
    023     *
    024     * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
    025     * in the United States and other countries.]
    026     *
    027     * ------------------
    028     * JTextObserver.java
    029     * ------------------
    030     * (C) Copyright 2004, by Thomas Morgner and Contributors.
    031     *
    032     * Original Author:  Thomas Morgner;
    033     * Contributor(s):   David Gilbert (for Object Refinery Limited);
    034     *
    035     * $Id: JTextObserver.java,v 1.5 2005/10/18 13:18:34 mungady Exp $
    036     *
    037     * Changes
    038     * -------
    039     * 07-Jun-2004 : Added JCommon header (DG);
    040     *
    041     */
    042
    043    package org.jfree.ui;
    044
    045    import java.awt.event.FocusEvent;
    046    import java.awt.event.FocusListener;
    047
    048    import javax.swing.text.JTextComponent;
    049
    050    /**
    051     * An observer that selects all the text when a field gains the focus.
    052     *
    053     * @author Thomas Morgner
    054     */
    055    public final class JTextObserver implements FocusListener {
    056
    057        /** The singleton instance. */
    058        private static JTextObserver singleton;
    059
    060        /**
    061         * Creates a new instance.
    062         */
    063        private JTextObserver() {
    064            // nothing required
    065        }
    066
    067        /**
    068         * Returns the single instance.
    069         *
    070         * @return The single instance.
    071         */
    072        public static JTextObserver getInstance() {
    073            if (singleton == null) {
    074               singleton = new JTextObserver();
    075            }
    076            return singleton;
    077        }
    078
    079        /**
    080         * Selects all the text when a field gains the focus.
    081         *
    082         * @param e  the focus event.
    083         */
    084        public void focusGained(final FocusEvent e) {
    085            if (e.getSource() instanceof JTextComponent) {
    086                final JTextComponent tex = (JTextComponent) e.getSource();
    087                tex.selectAll();
    088            }
    089        }
    090
    091        /**
    092         * Deselects the text when a field loses the focus.
    093         *
    094         * @param e  the event.
    095         */
    096        public void focusLost(final FocusEvent e) {
    097            if (e.getSource() instanceof JTextComponent) {
    098                final JTextComponent tex = (JTextComponent) e.getSource();
    099                tex.select(0, 0);
    100            }
    101        }
    102
    103        /**
    104         * Adds this instance as a listener for the specified text component.
    105         *
    106         * @param t  the text component.
    107         */
    108        public static void addTextComponent(final JTextComponent t) {
    109            if (singleton == null) {
    110                singleton = new JTextObserver();
    111            }
    112            t.addFocusListener(singleton);
    113        }
    114
    115        /**
    116         * Removes this instance as a listener for the specified text component.
    117         *
    118         * @param t  the text component.
    119         */
    120       public static void removeTextComponent(final JTextComponent t) {
    121            if (singleton == null) {
    122                singleton = new JTextObserver();
    123            }
    124            t.removeFocusListener(singleton);
    125        }
    126
    127    }