/Users/richardallenbair/Documents/Source/Projects/nonsense/swingx/src/beaninfo/JavaBean_API.java
/*
 * $Id: JavaBean_API.html 1302 2006-07-31 17:58:46Z rbair $
 *
 * Copyright 2004 Sun Microsystems, Inc., 4150 Network Circle,
 * Santa Clara, California 95054, U.S.A. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

package org.jdesktop.swingx;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;

/**
 * <p>A convenience class from which to extend all non-visual JavaBeans. It
 * manages the PropertyChange notification system, making it relatively trivial
 * to add support for property change events in getters/setters.</p>
 *
 * <p>Here is a simple example bean that contains one property, foo, and the
 * proper pattern for implementing property change notification:
 * <pre><code>
 *  public class ABean extends JavaBean {
 *    private String foo;
 *    
 *    public void setFoo(String newFoo) {
 *      String old = getFoo();
 *      this.foo = newFoo;
 *      firePropertyChange("foo", old, getFoo());
 *    }
 *
 *    public String getFoo() {
 *      return foo;
 *    }
 *  }
 * </code></pre></p>
 *
 * <p>You will notice that "getFoo()" is used in the setFoo method rather than
 * accessing "foo" directly for the gets. This is done intentionally so that if
 * a subclass overrides getFoo() to return, for instance, a constant value the
 * property change notification system will continue to work properly.</p>
 *
 * <p>The firePropertyChange method takes into account the old value and the new
 * value. Only if the two differ will it fire a property change event. So you can
 * be assured from the above code fragment that a property change event will only
 * occur if old is indeed different from getFoo()</p>
 *
 * @author rbair
 */
public class JavaBean {
    /** Creates a new instance of JavaBean */
    protected JavaBean();
    
    /**
     * Add a PropertyChangeListener to the listener list.
     * The listener is registered for all properties.
     * The same listener object may be added more than once, and will be called
     * as many times as it is added.
     * If <code>listener</code> is null, no exception is thrown and no action
     * is taken.
     *
     * @param listener  The PropertyChangeListener to be added
     */
    public void addPropertyChangeListener(PropertyChangeListener listener);

    /**
     * Remove a PropertyChangeListener from the listener list.
     * This removes a PropertyChangeListener that was registered
     * for all properties.
     * If <code>listener</code> was added more than once to the same event
     * source, it will be notified one less time after being removed.
     * If <code>listener</code> is null, or was never added, no exception is
     * thrown and no action is taken.
     *
     * @param listener  The PropertyChangeListener to be removed
     */
    public void removePropertyChangeListener(PropertyChangeListener listener);

    /**
     * Returns an array of all the listeners that were added to the
     * PropertyChangeSupport object with addPropertyChangeListener().
     * <p>
     * If some listeners have been added with a named property, then
     * the returned array will be a mixture of PropertyChangeListeners
     * and <code>PropertyChangeListenerProxy</code>s. If the calling
     * method is interested in distinguishing the listeners then it must
     * test each element to see if it's a
     * <code>PropertyChangeListenerProxy</code>, perform the cast, and examine
     * the parameter.
     * 
     * <pre>
     * PropertyChangeListener[] listeners = bean.getPropertyChangeListeners();
     * for (int i = 0; i < listeners.length; i++) {
     *   if (listeners[i] instanceof PropertyChangeListenerProxy) {
     *     PropertyChangeListenerProxy proxy = 
     *                    (PropertyChangeListenerProxy)listeners[i];
     *     if (proxy.getPropertyName().equals("foo")) {
     *       // proxy is a PropertyChangeListener which was associated
     *       // with the property named "foo"
     *     }
     *   }
     * }
     *</pre>
     *
     * @see java.beans.PropertyChangeListenerProxy
     * @return all of the <code>PropertyChangeListeners</code> added or an 
     *         empty array if no listeners have been added
     */
    public PropertyChangeListener[] getPropertyChangeListeners();

    /**
     * Add a PropertyChangeListener for a specific property.  The listener
     * will be invoked only when a call on firePropertyChange names that
     * specific property.
     * The same listener object may be added more than once.  For each
     * property,  the listener will be invoked the number of times it was added
     * for that property.
     * If <code>propertyName</code> or <code>listener</code> is null, no
     * exception is thrown and no action is taken.
     *
     * @param propertyName  The name of the property to listen on.
     * @param listener  The PropertyChangeListener to be added
     */
    public void addPropertyChangeListener(String propertyName, PropertyChangeListener listener);

    /**
     * Remove a PropertyChangeListener for a specific property.
     * If <code>listener</code> was added more than once to the same event
     * source for the specified property, it will be notified one less time
     * after being removed.
     * If <code>propertyName</code> is null,  no exception is thrown and no
     * action is taken.
     * If <code>listener</code> is null, or was never added for the specified
     * property, no exception is thrown and no action is taken.
     *
     * @param propertyName  The name of the property that was listened on.
     * @param listener  The PropertyChangeListener to be removed
     */
    public void removePropertyChangeListener(String propertyName, PropertyChangeListener listener);

    /**
     * Returns an array of all the listeners which have been associated 
     * with the named property.
     *
     * @param propertyName  The name of the property being listened to
     * @return all of the <code>PropertyChangeListeners</code> associated with
     *         the named property.  If no such listeners have been added,
     *         or if <code>propertyName</code> is null, an empty array is
     *         returned.
     */
    public PropertyChangeListener[] getPropertyChangeListeners(String propertyName);

    /**
     * Report a bound property update to any registered listeners.
     * No event is fired if old and new are equal and non-null.
     *
     * <p>
     * This is merely a convenience wrapper around the more general
     * firePropertyChange method that takes {@code
     * PropertyChangeEvent} value.
     *
     * @param propertyName  The programmatic name of the property
     *          that was changed.
     * @param oldValue  The old value of the property.
     * @param newValue  The new value of the property.
     */
    public void firePropertyChange(String propertyName, Object oldValue, Object newValue);

    /**
     * Report an int bound property update to any registered listeners.
     * No event is fired if old and new are equal.
     * <p>
     * This is merely a convenience wrapper around the more general
     * firePropertyChange method that takes Object values.
     *
     * @param propertyName  The programmatic name of the property
     *          that was changed.
     * @param oldValue  The old value of the property.
     * @param newValue  The new value of the property.
     */
    public void firePropertyChange(String propertyName, int oldValue, int newValue);


    /**
     * Report a boolean bound property update to any registered listeners.
     * No event is fired if old and new are equal.
     * <p>
     * This is merely a convenience wrapper around the more general
     * firePropertyChange method that takes Object values.
     *
     * @param propertyName  The programmatic name of the property
     *          that was changed.
     * @param oldValue  The old value of the property.
     * @param newValue  The new value of the property.
     */
    public void firePropertyChange(String propertyName, boolean oldValue, boolean newValue);

    /**
     * Fire an existing PropertyChangeEvent to any registered listeners.
     * No event is fired if the given event's old and new values are
     * equal and non-null.
     * @param evt  The PropertyChangeEvent object.
     */
    public void firePropertyChange(PropertyChangeEvent evt);

    
    /**
     * Report a bound indexed property update to any registered
     * listeners. 
     * <p>
     * No event is fired if old and new values are equal
     * and non-null.
     *
     * <p>
     * This is merely a convenience wrapper around the more general
     * firePropertyChange method that takes {@code PropertyChangeEvent} value.
     *
     * @param propertyName The programmatic name of the property that
     *                     was changed.
     * @param index        index of the property element that was changed.
     * @param oldValue     The old value of the property.
     * @param newValue     The new value of the property.
     */
    public void fireIndexedPropertyChange(String propertyName, int index,
                                          Object oldValue, Object newValue);

    /**
     * Report an <code>int</code> bound indexed property update to any registered 
     * listeners. 
     * <p>
     * No event is fired if old and new values are equal.
     * <p>
     * This is merely a convenience wrapper around the more general
     * fireIndexedPropertyChange method which takes Object values.
     *
     * @param propertyName The programmatic name of the property that
     *                     was changed.
     * @param index        index of the property element that was changed.
     * @param oldValue     The old value of the property.
     * @param newValue     The new value of the property.
     */
    public void fireIndexedPropertyChange(String propertyName, int index,
                                          int oldValue, int newValue);

    /**
     * Report a <code>boolean</code> bound indexed property update to any 
     * registered listeners. 
     * <p>
     * No event is fired if old and new values are equal.
     * <p>
     * This is merely a convenience wrapper around the more general
     * fireIndexedPropertyChange method which takes Object values.
     *
     * @param propertyName The programmatic name of the property that
     *                     was changed.
     * @param index        index of the property element that was changed.
     * @param oldValue     The old value of the property.
     * @param newValue     The new value of the property.
     */
    public void fireIndexedPropertyChange(String propertyName, int index,
                                          boolean oldValue, boolean newValue);

    /**
     * Check if there are any listeners for a specific property, including
     * those registered on all properties.  If <code>propertyName</code>
     * is null, only check for listeners registered on all properties.
     *
     * @param propertyName  the property name.
     * @return true if there are one or more listeners for the given property
     */
    public boolean hasListeners(String propertyName);
}