com.sas.collection
Class CollectionMirror

com.sas.collection.CollectionMirror

All Implemented Interfaces:

com.sas.beans.PropertyChangeSource, com.sas.beans.VetoableChangeSource, com.sas.collection.ContentsChangedListener, com.sas.collection.ContentsChangedSource, StaticCollectionInterface, ComponentInterface, LinkPropertiesInterface, ModelInterface, com.sas.PublicClonable, com.sas.util.Countable, com.sas.util.Enumerable, com.sas.util.EventGateInterface, ViewInterface, MultipleValueEventSourceInterface, java.beans.PropertyChangeListener, java.io.ObjectInputValidation, java.io.Serializable, java.lang.Cloneable, java.util.EventListener

Direct Known Subclasses:

StaticCollection, StaticStringList

public abstract class CollectionMirror
implements com.sas.collection.ContentsChangedListener

A CollectionMirror is an abstract base class for other read-only collections which "reflect" other collections. That is, the mirror class provides read-only access to another collection, but does not provide update methods. A CollectionMirror is useful for classes which wish to provide read-only access to collections they manage internally, but do not wish to allow other objects to change those internal collection.

See StaticOrderedCollection for a case when a CollectionMirror is used.

The CollectionMirror manages ContentsChangedEvents. The mirror allows listeners to listen for ContentsChangeEvents. If the mirror has listeners, then the mirror will itself listen for ContentsChangeEvents from the original collection, and when it changes, the mirror will send a ContentsChangeEvent to all listeners. If all listeners detach from the mirror, the mirror will remove itself from the original collection.

This is an important note, because as long as there are listeners, the mirror object will itself be a listener on the original collection, which means the mirror cannot be garbage collected (the reflected collection has a reference to the mirror in its ContentsChangedEvent listener list.)

See Also:

StaticCollection, StaticOrderedCollection, StaticDictionary, StaticStringList, Serialized Form

Field Summary

Fields inherited from class com.sas.collection.BaseCollection

allContentsChangedListeners, mappingObject

Constructor Summary

protected

CollectionMirror(com.sas.collection.ContentsChangedSource source) Construct a collection mirror.

Method Summary

void	addContentsChangedListener(com.sas.collection.ContentsChangedListener listener) Add a listener for the com.sas.util.ContentsChangedEvent event.
java.lang.Object	clone() Clone the collection.
void	contentsChanged(com.sas.collection.ContentsChangedEvent event) Handle a change event from the original collection.
boolean	equals(java.lang.Object object) Test object equality.
protected com.sas.collection.ContentsChangedSource	getSource() Return the source object that was passed in to the constructor.
int	hashCode() Compute the object's hash code.
void	removeContentsChangedListener(com.sas.collection.ContentsChangedListener listener) Remove a listener for the com.sas.util.ContentsChangedEvent event.
java.lang.String	toString() Convert the object to a string.

Methods inherited from class com.sas.collection.BaseCollection

anyContentsChangedListeners, apply, contains, count, disableEvents, enableEvents, enableEvents, fireContentsChanged, getItems, map, unmap

Methods inherited from class com.sas.Component

addLink, addPropertyChangeListener, addVetoableChangeListener, anyPropertyChangeListeners, attachModel, attachView, beansIsDesignTime, beansSetDesignTime, clone, detachModel, detachView, dumpComponent, firePropertyChange, firePropertyChange, fireVetoableChange, getComponentDescription, getComponentSupportInfo, getEventMethod, getEventValues, getExtendedBeanInfo, getLinkInfo, getModelInterface, getRequiredInterfaces, getResources, getStringResource, getViewInterfaceSupportInfo, initialize, initializeComponent, isDesignTime, isLinked, propertyChange, queryLinks, queryLinks, refresh, removeAllLinks, removeInterfaceTraps, removeLink, removePropertyChangeListener, removeVetoableChangeListener, setComponentDescription, setComponentSupportInfo, setDefaultValues, setLinkInfo, setModelInterface, setRequiredInterfaces, setViewInterfaceSupportInfo, supportsListenerInterface, supportsRequiredInterfaces, trapInterfaceEvents, validateObject

Methods inherited from interface com.sas.beans.PropertyChangeSource

addPropertyChangeListener, removePropertyChangeListener

Constructor Detail

CollectionMirror

protected CollectionMirror(com.sas.collection.ContentsChangedSource source)

Construct a collection mirror. This object will reflect the source collection.

Parameters:

source - another collection that acts as a source of ContentsChangedEvent events.

Method Detail

getSource

protected final com.sas.collection.ContentsChangedSource getSource()

Return the source object that was passed in to the constructor. This method is not public, because the mirror owner may not want to reveal the source collection.

Returns:

the source collection that this mirror reflects.

addContentsChangedListener

public void addContentsChangedListener(com.sas.collection.ContentsChangedListener listener)

Add a listener for the com.sas.util.ContentsChangedEvent event.

Specified by:

addContentsChangedListener in interface com.sas.collection.ContentsChangedSource

Overrides:

addContentsChangedListener in class BaseCollection

Parameters:

listener - an object which handles ContentsChangedEvent events the listener is not added a second time if it already exists in the list of listeners for this event.

See Also:

ContentsChangedSource

removeContentsChangedListener

public void removeContentsChangedListener(com.sas.collection.ContentsChangedListener listener)

Remove a listener for the com.sas.util.ContentsChangedEvent event. Nothing happens if the listener is not in the list of listeners for this event.

Specified by:

removeContentsChangedListener in interface com.sas.collection.ContentsChangedSource

Overrides:

removeContentsChangedListener in class BaseCollection

Parameters:

listener - an object which handles ContentsChangedEvent events

See Also:

ContentsChangedSource

contentsChanged

public void contentsChanged(com.sas.collection.ContentsChangedEvent event)

Handle a change event from the original collection. A new ContentsChangedEvent is fired, with this mirror as the source (since this mirror is what the listener is listening to, we should not simply resend the event, since it's getSourc() method would then reveal the identity of the actual collection we're mirroring.)

Specified by:

contentsChanged in interface com.sas.collection.ContentsChangedListener

Parameters:

event - an event from the original source.

toString

public java.lang.String toString()

Convert the object to a string. This defers to the underlying collection.

Overrides:

toString in class java.lang.Object

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException

Clone the collection.

Specified by:

clone in interface StaticCollectionInterface

Specified by:

clone in interface com.sas.PublicClonable

Overrides:

clone in class BaseCollection

Returns:

a clone of the mirror. The underlying collection is also cloned, if it is PublicClonable.

Throws:

java.lang.CloneNotSupportedException - is the mirror or the underlying collection cannot be cloned.

hashCode

public int hashCode()

Compute the object's hash code.

Overrides:

hashCode in class java.lang.Object

Returns:

the underlying component's hash code.

equals

public boolean equals(java.lang.Object object)

Test object equality.

Overrides:

equals in class java.lang.Object

Returns:

true if this object equals another object, else return false