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Class javax.infobus.DataItemChangeSupport 

java.lang.Object
   |
   +----javax.infobus.DataItemChangeSupport
public class DataItemChangeSupport
extends Object
This class implements the methods defined by DataItemChangeManager for managing event listeners, and adds specialized methods for firing each type of change notification. A class that implements DataItemChangeManager can delegate the work for its methods to the methods defined here, and the various methods in access interfaces that allow changes to data can fire events using methods defined here.

Version:
$Revision: 1.9 $ $Date: 08 Mar 1998 22:44:18 $
See Also:
DataItemChangeManager

Variable Index

o m_changeListeners
A Vector containing all registered DataItemChangeListeners.
o m_source
The Object that implements DataItemChangeManager, representing the source of the event.

Constructor Index

o DataItemChangeSupport(Object)
The constructor initializes an event indicating a change to a data item.

Method Index

o addDataItemChangeListener(DataItemChangeListener)
Adds a change listener as requested by a consumer or other InfoBus component.
o enumerateListeners()
Returns an enumeration of a clone of the listener list.
o fireItemAdded(Object, Object, InfoBusPropertyMap)
This method is called when one or more new items are being added to a collection.
o fireItemDeleted(Object, Object, InfoBusPropertyMap)
This method is called when one or more items are being removed from a collection.
o fireItemRevoked(Object, InfoBusPropertyMap)
This method is called when an item or collection is no longer available, such as when the data source is going offline.
o fireItemValueChanged(Object, InfoBusPropertyMap)
This method is called when an item, usually an ImmediateAccess, changes value.
o fireRowsetCursorMoved(Object, InfoBusPropertyMap)
This method should be called when a rowset's cursor has moved to a different row.
o removeAllListeners()
This method permits the owner of the data item using the DataItemChangeSupport to force removal of all registered listeners.
o removeDataItemChangeListener(DataItemChangeListener)
Removes a change listener as requested by a consumer or other InfoBus component.

Variables

o m_source 
 protected Object m_source
The Object that implements DataItemChangeManager, representing the source of the event. Set by the constructor, referenced when firing events.

o m_changeListeners 
 protected Vector m_changeListeners
A Vector containing all registered DataItemChangeListeners. This Vector is cloned and then the clone enumerated for event distribution.

Constructors

o DataItemChangeSupport 
 public DataItemChangeSupport(Object source)
The constructor initializes an event indicating a change to a data item.

Parameters:
source - the data item object that implements the DataItemChangeManager interface, representing the source of the event. When an instance of this class is a member field for a data item, the source is a reference to the outer class that contains the instance of this class.

Methods

o addDataItemChangeListener 
 public synchronized void addDataItemChangeListener(DataItemChangeListener listener)
Adds a change listener as requested by a consumer or other InfoBus component.

Parameters:
listener - the change listener object to be registered
o removeDataItemChangeListener 
 public synchronized void removeDataItemChangeListener(DataItemChangeListener listener)
Removes a change listener as requested by a consumer or other InfoBus component.

Parameters:
listener - the change listener object to be unregistered
o removeAllListeners 
 public synchronized void removeAllListeners()
This method permits the owner of the data item using the DataItemChangeSupport to force removal of all registered listeners. It should be called only after those listeners were delivered a DataItemRevoked event by calling DataItemChangeSupport.fireRevokedEvent AND an InfoBusItemRevokedEvent was sent on the InfoBus (by calling InfoBus.fireItemRevoked).

o enumerateListeners 
 protected synchronized Enumeration enumerateListeners()
Returns an enumeration of a clone of the listener list. By enumerating a clone, the returned enumeration is unaffected by additions or removals to the master list. Used by all fire methods.

Returns:
an Enumeration of a clone of the listener Vector, or null if that Vector is null.
o fireItemValueChanged 
 public void fireItemValueChanged(Object changedItem,
                                  InfoBusPropertyMap propertyMap)
This method is called when an item, usually an ImmediateAccess, changes value.

Parameters:
changedItem - the Object whose value changed.
o fireItemAdded 
 public void fireItemAdded(Object changedItem,
                           Object changedCollection,
                           InfoBusPropertyMap propertyMap)
This method is called when one or more new items are being added to a collection.

Parameters:
changedItem - the Object which was added, or null to indicate that more than one item was added.
changedCollection - the collection that gained a new item.
o fireItemDeleted 
 public void fireItemDeleted(Object changedItem,
                             Object changedCollection,
                             InfoBusPropertyMap propertyMap)
This method is called when one or more items are being removed from a collection.

Parameters:
changedItem - the Object which was removed, or null to indicate that more than one item was removed.
changedCollection - the collection that lost an item.
o fireItemRevoked 
 public void fireItemRevoked(Object changedItem,
                             InfoBusPropertyMap propertyMap)
This method is called when an item or collection is no longer available, such as when the data source is going offline. Unlike the other events, this event is sent to the data item passed during rendezvous, and to all sub-items in a collection hierarchy.

Parameters:
changedItem - the item or collection that is being revoked.
o fireRowsetCursorMoved 
 public void fireRowsetCursorMoved(Object changedItem,
                                   InfoBusPropertyMap propertyMap)
This method should be called when a rowset's cursor has moved to a different row.

Parameters:
changedItem - the rowset whose cursor changed. 
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