    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 1.6 2007/11/02 17:50:36 taqua 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    import javax.swing.text.JTextComponent;
    048
    049    /**
    050     * An observer that selects all the text when a field gains the focus.
    051     *
    052     * @author Thomas Morgner
    053     */
    054    public final class JTextObserver implements FocusListener {
    055
    056        /** The singleton instance. */
    057        private static JTextObserver singleton;
    058
    059        /**
    060         * Creates a new instance.
    061         */
    062        private JTextObserver() {
    063            // nothing required
    064        }
    065
    066        /**
    067         * Returns the single instance.
    068         *
    069         * @return The single instance.
    070         */
    071        public static JTextObserver getInstance() {
    072            if (singleton == null) {
    073               singleton = new JTextObserver();
    074            }
    075            return singleton;
    076        }
    077
    078        /**
    079         * Selects all the text when a field gains the focus.
    080         *
    081         * @param e  the focus event.
    082         */
    083        public void focusGained(final FocusEvent e) {
    084            if (e.getSource() instanceof JTextComponent) {
    085                final JTextComponent tex = (JTextComponent) e.getSource();
    086                tex.selectAll();
    087            }
    088        }
    089
    090        /**
    091         * Deselects the text when a field loses the focus.
    092         *
    093         * @param e  the event.
    094         */
    095        public void focusLost(final FocusEvent e) {
    096            if (e.getSource() instanceof JTextComponent) {
    097                final JTextComponent tex = (JTextComponent) e.getSource();
    098                tex.select(0, 0);
    099            }
    100        }
    101
    102        /**
    103         * Adds this instance as a listener for the specified text component.
    104         *
    105         * @param t  the text component.
    106         */
    107        public static void addTextComponent(final JTextComponent t) {
    108            if (singleton == null) {
    109                singleton = new JTextObserver();
    110            }
    111            t.addFocusListener(singleton);
    112        }
    113
    114        /**
    115         * Removes this instance as a listener for the specified text component.
    116         *
    117         * @param t  the text component.
    118         */
    119       public static void removeTextComponent(final JTextComponent t) {
    120            if (singleton == null) {
    121                singleton = new JTextObserver();
    122            }
    123            t.removeFocusListener(singleton);
    124        }
    125
    126    }