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/*******************************************************************************
* Copyright (c) 2007, 2008 Oracle. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0, which accompanies this distribution
* and is available at http://www.eclipse.org/legal/epl-v10.html.
*
* Contributors:
* Oracle - initial API and implementation
******************************************************************************/
package org.eclipse.jpt.utility.model.event;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import org.eclipse.jpt.utility.model.Model;
/**
* A "collection change" event gets delivered whenever a model changes a "bound"
* or "constrained" collection. A CollectionChangeEvent is sent as an
* argument to the CollectionChangeListener.
*
* Normally a CollectionChangeEvent is accompanied by the collection name and
* the items that were added to or removed from the changed collection.
*
* Design options:
* - create a collection to wrap a single added or removed item
* (this is the option we implemented below and in collaborating code)
* since there is no way to optimize downstream code for
* single items, we take another performance hit by building
* a collection each time (@see Collections#singleton(Object))
* and forcing downstream code to use an iterator every time
*
* - fire a separate event for each item added or removed
* eliminates any potential for optimizations to downstream code
*
* - add protocol to support both single items and collections
* adds conditional logic to downstream code
*
* Provisional API: This class is part of an interim API that is still
* under development and expected to change significantly before reaching
* stability. It is available at this early stage to solicit feedback from
* pioneering adopters on the understanding that any code that uses this API
* will almost certainly be broken (repeatedly) as the API evolves.
*/
public class CollectionChangeEvent extends ChangeEvent {
/** Name of the collection that changed. */
private final String collectionName;
/** The items that were added to or removed from the collection. May be empty, if not known. */
private final Collection<?> items;
private static final long serialVersionUID = 1L;
// ********** constructors **********
/**
* Construct a new collection change event.
*
* @param source The object on which the event initially occurred.
* @param collectionName The programmatic name of the collection that was changed.
* @param items The items that were added to or removed from the collection.
*/
public CollectionChangeEvent(Model source, String collectionName, Collection<?> items) {
super(source);
if ((collectionName == null) || (items == null)) {
throw new NullPointerException();
}
this.collectionName = collectionName;
this.items = Collections.unmodifiableCollection(items);
}
/**
* Construct a new collection change event.
*
* @param source The object on which the event initially occurred.
* @param collectionName The programmatic name of the collection that was changed.
*/
public CollectionChangeEvent(Model source, String collectionName) {
this(source, collectionName, Collections.emptySet());
}
// ********** standard state **********
/**
* Return the programmatic name of the collection that was changed.
*/
public String getCollectionName() {
return this.collectionName;
}
@Override
public String getAspectName() {
return this.collectionName;
}
/**
* Return an iterator on the items that were added to or
* removed from the collection.
* May be empty if inappropriate or unknown.
*/
public Iterator<?> items() {
return this.items.iterator();
}
/**
* Return the number of items that were added to or
* removed from the collection.
* May be 0 if inappropriate or unknown.
*/
public int itemsSize() {
return this.items.size();
}
// ********** cloning **********
/**
* Return a copy of the event with the specified source
* replacing the current source.
*/
@Override
public CollectionChangeEvent cloneWithSource(Model newSource) {
return new CollectionChangeEvent(newSource, this.collectionName, this.items);
}
/**
* Return a copy of the event with the specified source and collection name
* replacing the current source and collection name.
*/
public CollectionChangeEvent cloneWithSource(Model newSource, String newCollectionName) {
return new CollectionChangeEvent(newSource, newCollectionName, this.items);
}
}
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