File	Doc	Category	Size	Date	Package
PropertyChangeSupport.java	API Doc	Example	11236	Sun Dec 14 22:47:38 GMT 2003	oreilly.hcj.references

PropertyChangeSupport

• java.lang.Object

Fields Summary
private static final Logger	LOGGER Holds the logger instance for the class.
private static final String	ALL_PROPERTIES Holds the value used as the key for general listeners in the listener map. This value is chosen because it would be illegal to name a property the same as this value which guarantees that there will be no name clashes.
private final Map	listenerMap Holds the Listener map. The map is held as an index of WeakHashSet objects. Each property will appear as a key once in the set and when a property change event is fired on a property, the event will be fired to the union of the specific listeners set and the general listeners set. The general listeners are also held in the set with the key set by ALL_PROPERTIES
private final Object	producer Stores the producer of the events.

Constructors Summary

public PropertyChangeSupport(Object producer) Creates a new instance of SafePropertyChangeSupport. param producer This is the object that is producing the property change events. throws RuntimeException If there is an introspection problem. try { final BeanInfo info = Introspector.getBeanInfo(producer.getClass()); final PropertyDescriptor[] props = info.getPropertyDescriptors(); for (int idx = 0; idx < props.length; idx++) { listenerMap.put(props[idx].getName(), new WeakHashSet()); } listenerMap.put(ALL_PROPERTIES, new WeakHashSet()); this.producer = producer; } catch (IntrospectionException ex) { throw new RuntimeException(ex); }

Methods Summary
public void	addPropertyChangeListener(java.beans.PropertyChangeListener pcl) Add a non-specific PropertyChangeListener. Adds a listener that will recieve events on all properties. param pcl The PropertyChangeListener add. synchronized (listenerMap) { ((WeakHashSet)listenerMap.get(ALL_PROPERTIES)).add(pcl); }
public void	addPropertyChangeListener(java.lang.String property, java.beans.PropertyChangeListener pcl) Add a PropertyChangeListener for a specific property. param property The name of the relevant property. param pcl The listener to add. validateNamedProperty(property); synchronized (listenerMap) { ((WeakHashSet)listenerMap.get(property)).add(pcl); }
public void	firePropertyChange(java.lang.String property, java.lang.Object old, java.lang.Object neo) Notify listeners that an object type property has changed param property the name of the property which changed. param old The old value. param neo The new value. PropertyChangeEvent event = new PropertyChangeEvent(producer, property, old, neo); firePropertyChange(event);
public void	firePropertyChange(java.lang.String property, int old, int neo) Shortcut for firing an event on boolean properties. param property the name of the property which changed. param old The old value. param neo The new value. PropertyChangeEvent event = new PropertyChangeEvent(producer, property, new Integer(old), new Integer(neo)); firePropertyChange(event);
public void	firePropertyChange(java.lang.String property, boolean old, boolean neo) Shortcut for firing an event on boolean properties. param property the name of the property which changed. param old The old value. param neo The new value. PropertyChangeEvent event = new PropertyChangeEvent(producer, property, new Boolean(old), new Boolean(neo)); firePropertyChange(event);
public void	firePropertyChange(java.beans.PropertyChangeEvent event) Fire a property change event to all of the listeners. This method is called by all the fire methods to perform the firing of the events. The firing will go to the listeners that are registered for the specific property as well as general purpose listeners. If the old and new values for the event are the same, by the equals() method, the event will not be fired. param event The event to fire to the listeners. validateNamedProperty(event.getPropertyName()); if (event.getOldValue() == null) { if (event.getOldValue() == null) { return; } } else if (event.getOldValue() .equals(event.getNewValue())) { return; } // validated that an event must be thrown; now throw it. synchronized (listenerMap) { // First gets the list of listeners and stores them in strong // references by copying them into a new set. Set targets = new HashSet((Set)listenerMap.get(ALL_PROPERTIES)); targets.addAll((Set)listenerMap.get(event.getPropertyName())); // Fire events at the listeners. Iterator iter = targets.iterator(); while (iter.hasNext()) { ((PropertyChangeListener)iter.next()).propertyChange(event); } // Release the strong set so that the weak refs take over again. }
public java.beans.PropertyChangeListener[]	getPropertyChangeListeners() Returns an array of all the listeners that were added to the PropertyChangeSupport object with addPropertyChangeListener(). The array is computed as late as possible to give as much cleanout time as neded. return An array of all listeners. Set all = new WeakHashSet(); PropertyChangeListener[] pcls = new PropertyChangeListener[0]; synchronized (listenerMap) { Iterator iter = listenerMap.values() .iterator(); while (iter.hasNext()) { all.addAll((Set)iter.next()); } } return (PropertyChangeListener[])all.toArray(pcls);
public java.beans.PropertyChangeListener[]	getPropertyChangeListeners(java.lang.String property) Returns an array of all the listeners which have been associated with the named property. param property The name of the relevant property. return An array of listeners listening to the specified property. validateNamedProperty(property); PropertyChangeListener[] pcls = new PropertyChangeListener[0]; Set namedListeners = null; synchronized (listenerMap) { namedListeners = new HashSet((Set)listenerMap.get(property)); } return (PropertyChangeListener[])namedListeners.toArray(pcls);
public boolean	hasListeners(java.lang.String property) Check if there are any listeners interested in a specific property. param property The relvant property name. return true If there are listeners for the given property validateNamedProperty(property); synchronized (listenerMap) { return (!((Set)listenerMap.get(property)).isEmpty()); }
public void	removePropertyChangeListener(java.beans.PropertyChangeListener pcl) Remove a PropertyChangeListener from the listener list. This removes a PropertyChangeListener that was registered for all properties. param pcl The PropertyChangeListener to be removed synchronized (listenerMap) { ((WeakHashSet)listenerMap.get(ALL_PROPERTIES)).remove(pcl); }
public void	removePropertyChangeListener(java.lang.String property, java.beans.PropertyChangeListener pcl) Remove a PropertyChangeListener for a specific property. param property The name of the relevant property. param pcl The listener to remove. validateNamedProperty(property); synchronized (listenerMap) { ((WeakHashSet)listenerMap.get(property)).remove(pcl); }
private void	validateNamedProperty(java.lang.String property) Validate that a property name is a member of the producer object. This is a helper method so that all methods that must validate this need not replicate the code. param property The name of the property to validate. throws IllegalArgumentException DOCUMENT ME! if (!listenerMap.containsKey(property)) { if (LOGGER.isDebugEnabled()) { LOGGER.debug("Key Set: " + listenerMap.keySet()); //$NON-NLS-1$ } throw new IllegalArgumentException("The property '" + property //$NON-NLS-1$ + "' is not a valid property of " //$NON-NLS-1$ + producer.getClass() + ". Valid values = " //$NON-NLS-1$ + listenerMap.keySet().toString()); }