JavaTM 2 Platform
Std. Ed. v1.4.2

java.beans
Class PropertyChangeSupport

java.lang.Object
  extended byjava.beans.PropertyChangeSupport
All Implemented Interfaces:
Serializable
Direct Known Subclasses:
SwingPropertyChangeSupport

public class PropertyChangeSupport
extends Object
implements Serializable

This is a utility class that can be used by beans that support bound properties. You can use an instance of this class as a member field of your bean and delegate various work to it. 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:
Serialized Form

Constructor Summary
PropertyChangeSupport(Object sourceBean)
          Constructs a PropertyChangeSupport object.
 
Method Summary
 void addPropertyChangeListener(PropertyChangeListener listener)
          Add a PropertyChangeListener to the listener list.
 void addPropertyChangeListener(String propertyName, PropertyChangeListener listener)
          Add a PropertyChangeListener for a specific property.
 void firePropertyChange(PropertyChangeEvent evt)
          Fire an existing PropertyChangeEvent to any registered listeners.
 void firePropertyChange(String propertyName, boolean oldValue, boolean newValue)
          Report a boolean bound property update to any registered listeners.
 void firePropertyChange(String propertyName, int oldValue, int newValue)
          Report an int bound property update to any registered listeners.
 void firePropertyChange(String propertyName, Object oldValue, Object newValue)
          Report a bound property update to any registered listeners.
 PropertyChangeListener[] getPropertyChangeListeners()
          Returns an array of all the listeners that were added to the PropertyChangeSupport object with addPropertyChangeListener().
 PropertyChangeListener[] getPropertyChangeListeners(String propertyName)
          Returns an array of all the listeners which have been associated with the named property.
 boolean hasListeners(String propertyName)
          Check if there are any listeners for a specific property.
 void removePropertyChangeListener(PropertyChangeListener listener)
          Remove a PropertyChangeListener from the listener list.
 void removePropertyChangeListener(String propertyName, PropertyChangeListener listener)
          Remove a PropertyChangeListener for a specific property.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

PropertyChangeSupport

public PropertyChangeSupport(Object sourceBean)
Constructs a PropertyChangeSupport object.

Parameters:
sourceBean - The bean to be given as the source for any events.
Method Detail

addPropertyChangeListener

public void addPropertyChangeListener(PropertyChangeListener listener)
Add a PropertyChangeListener to the listener list. The listener is registered for all properties.

Parameters:
listener - The PropertyChangeListener to be added

removePropertyChangeListener

public void removePropertyChangeListener(PropertyChangeListener listener)
Remove a PropertyChangeListener from the listener list. This removes a PropertyChangeListener that was registered for all properties.

Parameters:
listener - The PropertyChangeListener to be removed

getPropertyChangeListeners

public PropertyChangeListener[] getPropertyChangeListeners()
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"
     }
   }
 }

Returns:
all of the PropertyChangeListeners added or an empty array if no listeners have been added
Since:
1.4
See Also:
PropertyChangeListenerProxy

addPropertyChangeListener

public void addPropertyChangeListener(String propertyName,
                                      PropertyChangeListener listener)
Add a PropertyChangeListener for a specific property. The listener will be invoked only when a call on firePropertyChange names that specific property.

Parameters:
propertyName - The name of the property to listen on.
listener - The PropertyChangeListener to be added

removePropertyChangeListener

public void removePropertyChangeListener(String propertyName,
                                         PropertyChangeListener listener)
Remove a PropertyChangeListener for a specific property.

Parameters:
propertyName - The name of the property that was listened on.
listener - The PropertyChangeListener to be removed

getPropertyChangeListeners

public PropertyChangeListener[] getPropertyChangeListeners(String propertyName)
Returns an array of all the listeners which have been associated with the named property.

Returns:
all of the PropertyChangeListeners associated with the named property or an empty array if no listeners have been added

firePropertyChange

public void firePropertyChange(String propertyName,
                               Object oldValue,
                               Object newValue)
Report a bound property update to any registered listeners. No event is fired if old and new are equal and non-null.

Parameters:
propertyName - The programmatic name of the property that was changed.
oldValue - The old value of the property.
newValue - The new value of the property.

firePropertyChange

public void firePropertyChange(String propertyName,
                               int oldValue,
                               int newValue)
Report an int bound property update to any registered listeners. No event is fired if old and new are equal and non-null.

This is merely a convenience wrapper around the more general firePropertyChange method that takes Object values.

Parameters:
propertyName - The programmatic name of the property that was changed.
oldValue - The old value of the property.
newValue - The new value of the property.

firePropertyChange

public void firePropertyChange(String propertyName,
                               boolean oldValue,
                               boolean newValue)
Report a boolean bound property update to any registered listeners. No event is fired if old and new are equal and non-null.

This is merely a convenience wrapper around the more general firePropertyChange method that takes Object values.

Parameters:
propertyName - The programmatic name of the property that was changed.
oldValue - The old value of the property.
newValue - The new value of the property.

firePropertyChange

public void firePropertyChange(PropertyChangeEvent evt)
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.

Parameters:
evt - The PropertyChangeEvent object.

hasListeners

public boolean hasListeners(String propertyName)
Check if there are any listeners for a specific property.

Parameters:
propertyName - the property name.
Returns:
true if there are ore or more listeners for the given property

JavaTM 2 Platform
Std. Ed. v1.4.2

Submit a bug or feature
For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2003 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.


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