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/* * Copyright (c) 1997, 2008, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.swing; import javax.swing.event.*;import java.io.Serializable;import java.util.EventListener; /** * A generic implementation of SingleSelectionModel. * <p> * <strong>Warning:</strong> * Serialized objects of this class will not be compatible with * future Swing releases. The current serialization support is * appropriate for short term storage or RMI between applications running * the same version of Swing.  As of 1.4, support for long term storage * of all JavaBeans<sup><font size="-2">TM</font></sup> * has been added to the <code>java.beans</code> package. * Please see {@link java.beans.XMLEncoder}. * * @author Dave Moore */public class DefaultSingleSelectionModel implements SingleSelectionModel,Serializable {    /* Only one ModelChangeEvent is needed per model instance since the     * event's only (read-only) state is the source property.  The source     * of events generated here is always "this".     */    protected transient ChangeEvent changeEvent = null;    /** The collection of registered listeners */    protected EventListenerList listenerList = new EventListenerList();     private int index = -1;     // implements javax.swing.SingleSelectionModel    public int getSelectedIndex() {        return index;    }     // implements javax.swing.SingleSelectionModel    public void setSelectedIndex(int index) {        if (this.index != index) {            this.index = index;            fireStateChanged();        }    }     // implements javax.swing.SingleSelectionModel    public void clearSelection() {        setSelectedIndex(-1);    }     // implements javax.swing.SingleSelectionModel    public boolean isSelected() {        boolean ret = false;        if (getSelectedIndex() != -1) {            ret = true;        }        return ret;    }     /**     * Adds a <code>ChangeListener</code> to the button.     */    public void addChangeListener(ChangeListener l) {        listenerList.add(ChangeListener.class, l);    }     /**     * Removes a <code>ChangeListener</code> from the button.     */    public void removeChangeListener(ChangeListener l) {        listenerList.remove(ChangeListener.class, l);    }     /**     * Returns an array of all the change listeners     * registered on this <code>DefaultSingleSelectionModel</code>.     *     * @return all of this model's <code>ChangeListener</code>s     *         or an empty     *         array if no change listeners are currently registered     *     * @see #addChangeListener     * @see #removeChangeListener     *     * @since 1.4     */    public ChangeListener[] getChangeListeners() {        return listenerList.getListeners(ChangeListener.class);    }     /**     * Notifies all listeners that have registered interest for     * notification on this event type.  The event instance     * is created lazily.     * @see EventListenerList     */    protected void fireStateChanged() {        // Guaranteed to return a non-null array        Object[] listeners = listenerList.getListenerList();        // Process the listeners last to first, notifying        // those that are interested in this event        for (int i = listeners.length-2; i>=0; i-=2) {            if (listeners[i]==ChangeListener.class) {                // Lazily create the event:                if (changeEvent == null)                    changeEvent = new ChangeEvent(this);                ((ChangeListener)listeners[i+1]).stateChanged(changeEvent);            }        }    }     /**     * Returns an array of all the objects currently registered as     * <code><em>Foo</em>Listener</code>s     * upon this model.     * <code><em>Foo</em>Listener</code>s     * are registered using the <code>add<em>Foo</em>Listener</code> method.     * <p>     * You can specify the <code>listenerType</code> argument     * with a class literal, such as <code><em>Foo</em>Listener.class</code>.     * For example, you can query a <code>DefaultSingleSelectionModel</code>     * instance <code>m</code>     * for its change listeners     * with the following code:     *     * <pre>ChangeListener[] cls = (ChangeListener[])(m.getListeners(ChangeListener.class));</pre>     *     * If no such listeners exist,     * this method returns an empty array.     *     * @param listenerType  the type of listeners requested;     *          this parameter should specify an interface     *          that descends from <code>java.util.EventListener</code>     * @return an array of all objects registered as     *          <code><em>Foo</em>Listener</code>s     *          on this model,     *          or an empty array if no such     *          listeners have been added     * @exception ClassCastException if <code>listenerType</code> doesn't     *          specify a class or interface that implements     *          <code>java.util.EventListener</code>     *     * @see #getChangeListeners     *     * @since 1.3     */    public <T extends EventListener> T[] getListeners(Class<T> listenerType) {        return listenerList.getListeners(listenerType);    }}