https://openjdk.java.net/ 
/*
 * Copyright (c) 1996, 2013, 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
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 * questions.
 */
package java.beans;

import java.io.Serializable;
import java.io.ObjectStreamField;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import java.util.Hashtable;
import java.util.Map.Entry;


This is a utility class that can be used by beans that support bound properties. It manages a list of listeners and dispatches PropertyChangeEvents to them. You can use an instance of this class as a member field of your bean and delegate these types of work to it. The PropertyChangeListener can be registered for all properties or for a property specified by name. 
 Here is an example of PropertyChangeSupport usage that follows the rules and recommendations laid out in the JavaBeans™ specification: 
public class MyBean {
    private final PropertyChangeSupport pcs = new PropertyChangeSupport(this);
    public void addPropertyChangeListener(PropertyChangeListener listener) {
        this.pcs.addPropertyChangeListener(listener);
    }
    public void removePropertyChangeListener(PropertyChangeListener listener) {
        this.pcs.removePropertyChangeListener(listener);
    }
    private String value;
    public String getValue() {
        return this.value;
    }
    public void setValue(String newValue) {
        String oldValue = this.value;
        this.value = newValue;
        this.pcs.firePropertyChange("value", oldValue, newValue);
    }
    [...]
}



 A PropertyChangeSupport instance is thread-safe. 

This class is serializable.  When it is serialized it will save
(and restore) any listeners that are themselves serializable.  Any
non-serializable listeners will be skipped during serialization.

See Also:
Since:1.1
/**
 * This is a utility class that can be used by beans that support bound
 * properties.  It manages a list of listeners and dispatches
 * {@link PropertyChangeEvent}s to them.  You can use an instance of this class
 * as a member field of your bean and delegate these types of work to it.
 * The {@link PropertyChangeListener} can be registered for all properties
 * or for a property specified by name.
 * <p>
 * Here is an example of {@code PropertyChangeSupport} usage that follows
 * the rules and recommendations laid out in the JavaBeans&trade; specification:
 * <pre>
 * public class MyBean {
 *     private final PropertyChangeSupport pcs = new PropertyChangeSupport(this);
 *
 *     public void addPropertyChangeListener(PropertyChangeListener listener) {
 *         this.pcs.addPropertyChangeListener(listener);
 *     }
 *
 *     public void removePropertyChangeListener(PropertyChangeListener listener) {
 *         this.pcs.removePropertyChangeListener(listener);
 *     }
 *
 *     private String value;
 *
 *     public String getValue() {
 *         return this.value;
 *     }
 *
 *     public void setValue(String newValue) {
 *         String oldValue = this.value;
 *         this.value = newValue;
 *         this.pcs.firePropertyChange("value", oldValue, newValue);
 *     }
 *
 *     [...]
 * }
 * </pre>
 * <p>
 * A {@code PropertyChangeSupport} instance is thread-safe.
 * <p>
 * This class is serializable.  When it is serialized it will save
 * (and restore) any listeners that are themselves serializable.  Any
 * non-serializable listeners will be skipped during serialization.
 *
 * @see VetoableChangeSupport
 * @since 1.1
 */
public class PropertyChangeSupport implements Serializable {
    private PropertyChangeListenerMap map = new PropertyChangeListenerMap();

    
Constructs a PropertyChangeSupport object. 
Params:
  • sourceBean –  The bean to be given as the source for any events.
/**
     * Constructs a {@code PropertyChangeSupport} object.
     *
     * @param sourceBean  The bean to be given as the source for any events.
     */
    public PropertyChangeSupport(Object sourceBean) {
        if (sourceBean == null) {
            throw new NullPointerException();
        }
        source = sourceBean;
    }

    
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 listener is null, no exception is thrown and no action is taken. 
Params:
  • listener –  The PropertyChangeListener to be added
/**
     * 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} is null, no exception is thrown and no action
     * is taken.
     *
     * @param listener  The PropertyChangeListener to be added
     */
    public void addPropertyChangeListener(PropertyChangeListener listener) {
        if (listener == null) {
            return;
        }
        if (listener instanceof PropertyChangeListenerProxy) {
            PropertyChangeListenerProxy proxy =
                   (PropertyChangeListenerProxy)listener;
            // Call two argument add method.
            addPropertyChangeListener(proxy.getPropertyName(),
                                      proxy.getListener());
        } else {
            this.map.add(null, listener);
        }
    }

    
Remove a PropertyChangeListener from the listener list. This removes a PropertyChangeListener that was registered for all properties. If listener was added more than once to the same event source, it will be notified one less time after being removed. If listener is null, or was never added, no exception is thrown and no action is taken. 
Params:
  • listener –  The PropertyChangeListener to be removed
/**
     * Remove a PropertyChangeListener from the listener list.
     * This removes a PropertyChangeListener that was registered
     * for all properties.
     * If {@code listener} was added more than once to the same event
     * source, it will be notified one less time after being removed.
     * If {@code listener} 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) {
        if (listener == null) {
            return;
        }
        if (listener instanceof PropertyChangeListenerProxy) {
            PropertyChangeListenerProxy proxy =
                    (PropertyChangeListenerProxy)listener;
            // Call two argument remove method.
            removePropertyChangeListener(proxy.getPropertyName(),
                                         proxy.getListener());
        } else {
            this.map.remove(null, listener);
        }
    }

    
Returns an array of all the listeners that were added to the
PropertyChangeSupport object with addPropertyChangeListener().

 If some listeners have been added with a named property, then the returned array will be a mixture of PropertyChangeListeners and PropertyChangeListenerProxys. If the calling method is interested in distinguishing the listeners then it must test each element to see if it's a PropertyChangeListenerProxy, perform the cast, and examine the parameter. 

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"
    }
  }
 }



See Also:
Returns:all of the PropertyChangeListeners added or an empty array if no listeners have been added
Since:1.4
/**
     * 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}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}, perform the cast, and examine
     * the parameter.
     *
     * <pre>{@code
     * 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 PropertyChangeListenerProxy
     * @return all of the {@code PropertyChangeListeners} added or an
     *         empty array if no listeners have been added
     * @since 1.4
     */
    public PropertyChangeListener[] getPropertyChangeListeners() {
        return this.map.getListeners();
    }

    
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 propertyName or listener is null, no exception is thrown and no action is taken. 
Params:
  • propertyName –  The name of the property to listen on.
  • listener –  The PropertyChangeListener to be added
Since:1.2
/**
     * 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} or {@code listener} 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
     * @since 1.2
     */
    public void addPropertyChangeListener(
                String propertyName,
                PropertyChangeListener listener) {
        if (listener == null || propertyName == null) {
            return;
        }
        listener = this.map.extract(listener);
        if (listener != null) {
            this.map.add(propertyName, listener);
        }
    }

    
Remove a PropertyChangeListener for a specific property. If listener 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 propertyName is null, no exception is thrown and no action is taken. If listener is null, or was never added for the specified property, no exception is thrown and no action is taken. 
Params:
  • propertyName –  The name of the property that was listened on.
  • listener –  The PropertyChangeListener to be removed
Since:1.2
/**
     * Remove a PropertyChangeListener for a specific property.
     * If {@code listener} 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} is null,  no exception is thrown and no
     * action is taken.
     * If {@code listener} 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
     * @since 1.2
     */
    public void removePropertyChangeListener(
                String propertyName,
                PropertyChangeListener listener) {
        if (listener == null || propertyName == null) {
            return;
        }
        listener = this.map.extract(listener);
        if (listener != null) {
            this.map.remove(propertyName, listener);
        }
    }

    
Returns an array of all the listeners which have been associated
with the named property.

Params:
  • propertyName –  The name of the property being listened to
Returns:all of the PropertyChangeListeners associated with the named property. If no such listeners have been added, or if propertyName is null, an empty array is returned.
Since:1.4
/**
     * 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} associated with
     *         the named property.  If no such listeners have been added,
     *         or if {@code propertyName} is null, an empty array is
     *         returned.
     * @since 1.4
     */
    public PropertyChangeListener[] getPropertyChangeListeners(String propertyName) {
        return this.map.getListeners(propertyName);
    }

    
Reports a bound property update to listeners
that have been registered to track updates of
all properties or a property with the specified name.


No event is fired if old and new values are equal and non-null.

 This is merely a convenience wrapper around the more general firePropertyChange(PropertyChangeEvent) method. 
Params:
  • propertyName –  the programmatic name of the property that was changed
  • oldValue –      the old value of the property
  • newValue –      the new value of the property
/**
     * Reports a bound property update to listeners
     * that have been registered to track updates of
     * all properties or a property with the specified name.
     * <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
     * {@link #firePropertyChange(PropertyChangeEvent)} method.
     *
     * @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) {
        if (oldValue == null || newValue == null || !oldValue.equals(newValue)) {
            firePropertyChange(new PropertyChangeEvent(this.source, propertyName, oldValue, newValue));
        }
    }

    
Reports an integer bound property update to listeners
that have been registered to track updates of
all properties or a property with the specified name.


No event is fired if old and new values are equal.

 This is merely a convenience wrapper around the more general firePropertyChange(String, Object, Object) method. 
Params:
  • propertyName –  the programmatic name of the property that was changed
  • oldValue –      the old value of the property
  • newValue –      the new value of the property
Since:1.2
/**
     * Reports an integer bound property update to listeners
     * that have been registered to track updates of
     * all properties or a property with the specified name.
     * <p>
     * No event is fired if old and new values are equal.
     * <p>
     * This is merely a convenience wrapper around the more general
     * {@link #firePropertyChange(String, Object, Object)}  method.
     *
     * @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
     * @since 1.2
     */
    public void firePropertyChange(String propertyName, int oldValue, int newValue) {
        if (oldValue != newValue) {
            firePropertyChange(propertyName, Integer.valueOf(oldValue), Integer.valueOf(newValue));
        }
    }

    
Reports a boolean bound property update to listeners
that have been registered to track updates of
all properties or a property with the specified name.


No event is fired if old and new values are equal.

 This is merely a convenience wrapper around the more general firePropertyChange(String, Object, Object) method. 
Params:
  • propertyName –  the programmatic name of the property that was changed
  • oldValue –      the old value of the property
  • newValue –      the new value of the property
Since:1.2
/**
     * Reports a boolean bound property update to listeners
     * that have been registered to track updates of
     * all properties or a property with the specified name.
     * <p>
     * No event is fired if old and new values are equal.
     * <p>
     * This is merely a convenience wrapper around the more general
     * {@link #firePropertyChange(String, Object, Object)}  method.
     *
     * @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
     * @since 1.2
     */
    public void firePropertyChange(String propertyName, boolean oldValue, boolean newValue) {
        if (oldValue != newValue) {
            firePropertyChange(propertyName, Boolean.valueOf(oldValue), Boolean.valueOf(newValue));
        }
    }

    
Fires a property change event to listeners
that have been registered to track updates of
all properties or a property with the specified name.


No event is fired if the given event's old and new values are equal and non-null.

Params:
  • event –  the PropertyChangeEvent to be fired
Since:1.2
/**
     * Fires a property change event to listeners
     * that have been registered to track updates of
     * all properties or a property with the specified name.
     * <p>
     * No event is fired if the given event's old and new values are equal and non-null.
     *
     * @param event  the {@code PropertyChangeEvent} to be fired
     * @since 1.2
     */
    public void firePropertyChange(PropertyChangeEvent event) {
        Object oldValue = event.getOldValue();
        Object newValue = event.getNewValue();
        if (oldValue == null || newValue == null || !oldValue.equals(newValue)) {
            String name = event.getPropertyName();

            PropertyChangeListener[] common = this.map.get(null);
            PropertyChangeListener[] named = (name != null)
                        ? this.map.get(name)
                        : null;

            fire(common, event);
            fire(named, event);
        }
    }

    private static void fire(PropertyChangeListener[] listeners, PropertyChangeEvent event) {
        if (listeners != null) {
            for (PropertyChangeListener listener : listeners) {
                listener.propertyChange(event);
            }
        }
    }

    
Reports a bound indexed property update to listeners
that have been registered to track updates of
all properties or a property with the specified name.


No event is fired if old and new values are equal and non-null.

 This is merely a convenience wrapper around the more general firePropertyChange(PropertyChangeEvent) method. 
Params:
  • propertyName –  the programmatic name of the property that was changed
  • index –         the index of the property element that was changed
  • oldValue –      the old value of the property
  • newValue –      the new value of the property
Since:1.5
/**
     * Reports a bound indexed property update to listeners
     * that have been registered to track updates of
     * all properties or a property with the specified name.
     * <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
     * {@link #firePropertyChange(PropertyChangeEvent)} method.
     *
     * @param propertyName  the programmatic name of the property that was changed
     * @param index         the index of the property element that was changed
     * @param oldValue      the old value of the property
     * @param newValue      the new value of the property
     * @since 1.5
     */
    public void fireIndexedPropertyChange(String propertyName, int index, Object oldValue, Object newValue) {
        if (oldValue == null || newValue == null || !oldValue.equals(newValue)) {
            firePropertyChange(new IndexedPropertyChangeEvent(source, propertyName, oldValue, newValue, index));
        }
    }

    
Reports an integer bound indexed property update to listeners
that have been registered to track updates of
all properties or a property with the specified name.


No event is fired if old and new values are equal.

 This is merely a convenience wrapper around the more general fireIndexedPropertyChange(String, int, Object, Object) method. 
Params:
  • propertyName –  the programmatic name of the property that was changed
  • index –         the index of the property element that was changed
  • oldValue –      the old value of the property
  • newValue –      the new value of the property
Since:1.5
/**
     * Reports an integer bound indexed property update to listeners
     * that have been registered to track updates of
     * all properties or a property with the specified name.
     * <p>
     * No event is fired if old and new values are equal.
     * <p>
     * This is merely a convenience wrapper around the more general
     * {@link #fireIndexedPropertyChange(String, int, Object, Object)} method.
     *
     * @param propertyName  the programmatic name of the property that was changed
     * @param index         the index of the property element that was changed
     * @param oldValue      the old value of the property
     * @param newValue      the new value of the property
     * @since 1.5
     */
    public void fireIndexedPropertyChange(String propertyName, int index, int oldValue, int newValue) {
        if (oldValue != newValue) {
            fireIndexedPropertyChange(propertyName, index, Integer.valueOf(oldValue), Integer.valueOf(newValue));
        }
    }

    
Reports a boolean bound indexed property update to listeners
that have been registered to track updates of
all properties or a property with the specified name.


No event is fired if old and new values are equal.

 This is merely a convenience wrapper around the more general fireIndexedPropertyChange(String, int, Object, Object) method. 
Params:
  • propertyName –  the programmatic name of the property that was changed
  • index –         the index of the property element that was changed
  • oldValue –      the old value of the property
  • newValue –      the new value of the property
Since:1.5
/**
     * Reports a boolean bound indexed property update to listeners
     * that have been registered to track updates of
     * all properties or a property with the specified name.
     * <p>
     * No event is fired if old and new values are equal.
     * <p>
     * This is merely a convenience wrapper around the more general
     * {@link #fireIndexedPropertyChange(String, int, Object, Object)} method.
     *
     * @param propertyName  the programmatic name of the property that was changed
     * @param index         the index of the property element that was changed
     * @param oldValue      the old value of the property
     * @param newValue      the new value of the property
     * @since 1.5
     */
    public void fireIndexedPropertyChange(String propertyName, int index, boolean oldValue, boolean newValue) {
        if (oldValue != newValue) {
            fireIndexedPropertyChange(propertyName, index, Boolean.valueOf(oldValue), Boolean.valueOf(newValue));
        }
    }

    
Check if there are any listeners for a specific property, including those registered on all properties. If propertyName is null, only check for listeners registered on all properties. 
Params:
  • propertyName –  the property name.
Returns:true if there are one or more listeners for the given property
Since:1.2
/**
     * Check if there are any listeners for a specific property, including
     * those registered on all properties.  If {@code propertyName}
     * 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
     * @since 1.2
     */
    public boolean hasListeners(String propertyName) {
        return this.map.hasListeners(propertyName);
    }

    
@serialDataNull terminated list of PropertyChangeListeners. 

At serialization time we skip non-serializable listeners and
only serialize the serializable listeners.
/**
     * @serialData Null terminated list of {@code PropertyChangeListeners}.
     * <p>
     * At serialization time we skip non-serializable listeners and
     * only serialize the serializable listeners.
     */
    private void writeObject(ObjectOutputStream s) throws IOException {
        Hashtable<String, PropertyChangeSupport> children = null;
        PropertyChangeListener[] listeners = null;
        synchronized (this.map) {
            for (Entry<String, PropertyChangeListener[]> entry : this.map.getEntries()) {
                String property = entry.getKey();
                if (property == null) {
                    listeners = entry.getValue();
                } else {
                    if (children == null) {
                        children = new Hashtable<>();
                    }
                    PropertyChangeSupport pcs = new PropertyChangeSupport(this.source);
                    pcs.map.set(null, entry.getValue());
                    children.put(property, pcs);
                }
            }
        }
        ObjectOutputStream.PutField fields = s.putFields();
        fields.put("children", children);
        fields.put("source", this.source);
        fields.put("propertyChangeSupportSerializedDataVersion", 2);
        s.writeFields();

        if (listeners != null) {
            for (PropertyChangeListener l : listeners) {
                if (l instanceof Serializable) {
                    s.writeObject(l);
                }
            }
        }
        s.writeObject(null);
    }

    private void readObject(ObjectInputStream s) throws ClassNotFoundException, IOException {
        this.map = new PropertyChangeListenerMap();

        ObjectInputStream.GetField fields = s.readFields();

        @SuppressWarnings("unchecked")
        Hashtable<String, PropertyChangeSupport> children = (Hashtable<String, PropertyChangeSupport>) fields.get("children", null);
        this.source = fields.get("source", null);
        fields.get("propertyChangeSupportSerializedDataVersion", 2);

        Object listenerOrNull;
        while (null != (listenerOrNull = s.readObject())) {
            this.map.add(null, (PropertyChangeListener)listenerOrNull);
        }
        if (children != null) {
            for (Entry<String, PropertyChangeSupport> entry : children.entrySet()) {
                for (PropertyChangeListener listener : entry.getValue().getPropertyChangeListeners()) {
                    this.map.add(entry.getKey(), listener);
                }
            }
        }
    }

    
The object to be provided as the "source" for any generated events.

/**
     * The object to be provided as the "source" for any generated events.
     */
    private Object source;

    
@serialFieldchildren                                   Hashtable
@serialFieldsource                                     Object
@serialFieldpropertyChangeSupportSerializedDataVersion int
/**
     * @serialField children                                   Hashtable
     * @serialField source                                     Object
     * @serialField propertyChangeSupportSerializedDataVersion int
     */
    private static final ObjectStreamField[] serialPersistentFields = {
            new ObjectStreamField("children", Hashtable.class),
            new ObjectStreamField("source", Object.class),
            new ObjectStreamField("propertyChangeSupportSerializedDataVersion", Integer.TYPE)
    };

    
Serialization version ID, so we're compatible with JDK 1.1

/**
     * Serialization version ID, so we're compatible with JDK 1.1
     */
    static final long serialVersionUID = 6401253773779951803L;

    
This is a ChangeListenerMap implementation that works with PropertyChangeListener objects. 
/**
     * This is a {@link ChangeListenerMap ChangeListenerMap} implementation
     * that works with {@link PropertyChangeListener PropertyChangeListener} objects.
     */
    private static final class PropertyChangeListenerMap extends ChangeListenerMap<PropertyChangeListener> {
        private static final PropertyChangeListener[] EMPTY = {};

        
Creates an array of PropertyChangeListener objects. This method uses the same instance of the empty array when length equals 0. 
Params:
  • length –  the array length
Returns:       an array with specified length
/**
         * Creates an array of {@link PropertyChangeListener PropertyChangeListener} objects.
         * This method uses the same instance of the empty array
         * when {@code length} equals {@code 0}.
         *
         * @param length  the array length
         * @return        an array with specified length
         */
        @Override
        protected PropertyChangeListener[] newArray(int length) {
            return (0 < length)
                    ? new PropertyChangeListener[length]
                    : EMPTY;
        }

        
Creates a PropertyChangeListenerProxy object for the specified property. 
Params:
  • name –      the name of the property to listen on
  • listener –  the listener to process events
Returns: a PropertyChangeListenerProxy object
/**
         * Creates a {@link PropertyChangeListenerProxy PropertyChangeListenerProxy}
         * object for the specified property.
         *
         * @param name      the name of the property to listen on
         * @param listener  the listener to process events
         * @return          a {@code PropertyChangeListenerProxy} object
         */
        @Override
        protected PropertyChangeListener newProxy(String name, PropertyChangeListener listener) {
            return new PropertyChangeListenerProxy(name, listener);
        }

        
{@inheritDoc}

/**
         * {@inheritDoc}
         */
        public PropertyChangeListener extract(PropertyChangeListener listener) {
            while (listener instanceof PropertyChangeListenerProxy) {
                listener = ((PropertyChangeListenerProxy) listener).getListener();
            }
            return listener;
        }
    }
}