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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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.
 *
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package javax.swing;

import javax.swing.event.*;
import java.io.Serializable;
import java.util.EventListener;

A generic implementation of SingleSelectionModel.

Warning:
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
has been added to the java.beans package. Please see XMLEncoder. 
Author:
Dave Moore
Since:
1.2/**
 * 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
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @author Dave Moore
 * @since 1.2
 */
@SuppressWarnings("serial") // Same-version serialization only
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".
/**
     * 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 /** The collection of registered listeners */
    protected EventListenerList listenerList = new EventListenerList();

    private int index = -1;

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    public int getSelectedIndex() {
        return index;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    public void setSelectedIndex(int index) {
        if (this.index != index) {
            this.index = index;
            fireStateChanged();
        }
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    public void clearSelection() {
        setSelectedIndex(-1);
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    public boolean isSelected() {
        boolean ret = false;
        if (getSelectedIndex() != -1) {
            ret = true;
        }
        return ret;
    }

    
Adds a ChangeListener to the button.
/**
     * Adds a <code>ChangeListener</code> to the button.
     */
    public void addChangeListener(ChangeListener l) {
        listenerList.add(ChangeListener.class, l);
    }

    
Removes a ChangeListener from the button.
/**
     * 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 DefaultSingleSelectionModel.
See Also:
addChangeListener
removeChangeListener
Returns:
all of this model's ChangeListeners
        or an empty
        array if no change listeners are currently registered
Since:
1.4/**
     * 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 Also:
EventListenerList/**
     * 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
FooListeners
upon this model.
FooListeners
are registered using the addFooListener method.

You can specify the listenerType argument
with a class literal, such as FooListener.class.
For example, you can query a DefaultSingleSelectionModel
instance m
for its change listeners
with the following code:
ChangeListener[] cls = (ChangeListener[])(m.getListeners(ChangeListener.class));
If no such listeners exist,
this method returns an empty array.
Params:
listenerType –  the type of listeners requested;
         this parameter should specify an interface
         that descends from java.util.EventListener
Type parameters:
<T> –  the type of EventListener class being requested
Throws:
ClassCastException – if listenerType doesn't
         specify a class or interface that implements
         java.util.EventListener
See Also:
getChangeListeners
Returns:
an array of all objects registered as
         FooListeners
         on this model,
         or an empty array if no such
         listeners have been added
Since:
1.3/**
     * 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 <T>  the type of {@code EventListener} class being requested
     * @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);
    }
}