com.webobjects.eocontrol
Class EODelayedObserver

java.lang.Object
  com.webobjects.eocontrol.EODelayedObserver

All Implemented Interfaces:

EOObserving

Direct Known Subclasses:

EOAssociation, EOObserverProxy

public abstract class EODelayedObserver
extends Object
implements EOObserving

The EODelayedObserver class is a part of EOControl's change tracking mechanism. It is an abstract superclass that defines the basic functionality for coalescing change notifications for multiple objects and postponing notification according to a prioritized queue.

You would never create an instance of EODelayedObserver. Instead, you would use subclasses, typically subclasses of EOAssociation (defined in EOInterface).

See EODelayedObserverConcepts for more information.

See Also:

EODelayedObserverQueue

Field Summary

static int	ObserverNumberOfPriorities Constant to represent the number of priorities(8).
static int	ObserverPriorityFifth Constant to represent the priority of a notification in the queue.
static int	ObserverPriorityFirst Constant to represent the priority of a notification in the queue.
static int	ObserverPriorityFourth Constant to represent the priority of a notification in the queue.
static int	ObserverPriorityImmediate Constant to represent the priority of a notification in the queue.
static int	ObserverPriorityLater Constant to represent the priority of a notification in the queue.
static int	ObserverPrioritySecond Constant to represent the priority of a notification in the queue.
static int	ObserverPrioritySixth Constant to represent the priority of a notification in the queue.
static int	ObserverPriorityThird Constant to represent the priority of a notification in the queue.

Constructor Summary

EODelayedObserver()

Method Summary

void	discardPendingNotification() Sends a dequeueObserver message to the receiver's EODelayedObserverQueue to clear it from receiving a change notification.
void	objectWillChange(Object object) Implemented by EODelayedObserver to enqueue the receiver on its EODelayedObserverQueue.
EODelayedObserverQueue	observerQueue() Overridden by subclasses to determine the receiver's designated EODelayedObserverQueue.
int	priority() Overridden by subclasses to determine the receiver's change notification priority.
abstract void	subjectChanged() Implemented by subclasses to examine the receiver's observed objects and take whatever action is necessary.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ObserverPriorityImmediate

public static final int ObserverPriorityImmediate

Constant to represent the priority of a notification in the queue.

See Also:

Constant Field Values

ObserverPriorityFirst

public static final int ObserverPriorityFirst

Constant to represent the priority of a notification in the queue.

See Also:

Constant Field Values

ObserverPrioritySecond

public static final int ObserverPrioritySecond

Constant to represent the priority of a notification in the queue.

See Also:

Constant Field Values

ObserverPriorityThird

public static final int ObserverPriorityThird

Constant to represent the priority of a notification in the queue.

See Also:

Constant Field Values

ObserverPriorityFourth

public static final int ObserverPriorityFourth

Constant to represent the priority of a notification in the queue.

See Also:

Constant Field Values

ObserverPriorityFifth

public static final int ObserverPriorityFifth

Constant to represent the priority of a notification in the queue.

See Also:

Constant Field Values

ObserverPrioritySixth

public static final int ObserverPrioritySixth

Constant to represent the priority of a notification in the queue.

See Also:

Constant Field Values

ObserverPriorityLater

public static final int ObserverPriorityLater

Constant to represent the priority of a notification in the queue.

See Also:

Constant Field Values

ObserverNumberOfPriorities

public static final int ObserverNumberOfPriorities

Constant to represent the number of priorities(8).

See Also:

Constant Field Values

Constructor Detail

EODelayedObserver

public EODelayedObserver()

Method Detail

discardPendingNotification

public void discardPendingNotification()

Sends a dequeueObserver message to the receiver's EODelayedObserverQueue to clear it from receiving a change notification. A subclass of EODelayedObserver should invoke this method when its done observing changes.

See Also:

EODelayedObserver.observerQueue()

objectWillChange

public void objectWillChange(Object object)

Implemented by EODelayedObserver to enqueue the receiver on its EODelayedObserverQueue. Subclasses shouldn't need to override this method; if they do, they must be sure to invoke the superclass's implementation.

Specified by:

objectWillChange in interface EOObserving

Parameters:

object - the input object

See Also:

EODelayedObserver.observerQueue(), EODelayedObserverQueue.enqueueObserver(EODelayedObserver observer), EOObserving.objectWillChange(Object anObject)

priority

public int priority()

Overridden by subclasses to determine the receiver's change notification priority. The change notification is one of the following:

• ObserverPriorityImmediate
• ObserverPriorityFirst
• ObserverPrioritySecond
• ObserverPriorityThird
• ObserverPriorityFourth
• ObserverPriorityFifth
• ObserverPrioritySixth
• ObserverPriorityLater

The default implementation returns ObserverPriorityThird.

Returns:

ObserverPriorityThird

See Also:

EODelayedObserver.ObserverPriorityImmediate, EODelayedObserver.ObserverPriorityFirst, EODelayedObserver.ObserverPrioritySecond, EODelayedObserver.ObserverPriorityThird, EODelayedObserver.ObserverPriorityFourth, EODelayedObserver.ObserverPriorityFifth, EODelayedObserver.ObserverPrioritySixth, EODelayedObserver.ObserverPriorityLater, EODelayedObserverQueue, EODelayedObserver

observerQueue

public EODelayedObserverQueue observerQueue()

Overridden by subclasses to determine the receiver's designated EODelayedObserverQueue.

Returns:

the default EODelayedObserverQueue

See Also:

EODelayedObserverQueue.defaultObserverQueue()

subjectChanged

public abstract void subjectChanged()

Implemented by subclasses to examine the receiver's observed objects and take whatever action is necessary. The default implementation does nothing.