org.apache.commons.collections.collection
Class CompositeCollection

java.lang.Object
  org.apache.commons.collections.collection.CompositeCollection

All Implemented Interfaces:

java.lang.Iterable, java.util.Collection

Direct Known Subclasses:

CompositeSet

public class CompositeCollection
extends java.lang.Object
implements java.util.Collection

Decorates a collection of other collections to provide a single unified view.

Changes made to this collection will actually be made on the decorated collection. Add and remove operations require the use of a pluggable strategy. If no strategy is provided then add and remove are unsupported.

Since:

Commons Collections 3.0

Version:

$Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $

Author:

Brian McCallister, Stephen Colebourne, Phil Steitz

Nested Class Summary

static interface

CompositeCollection.CollectionMutator Pluggable strategy to handle changes to the composite.

Field Summary

protected java.util.Collection[]	all Collections in the composite
protected CompositeCollection.CollectionMutator	mutator CollectionMutator to handle changes to the collection

Constructor Summary

CompositeCollection()
Create an empty CompositeCollection.

CompositeCollection(java.util.Collection coll)
Create a Composite Collection with only coll composited.

CompositeCollection(java.util.Collection[] colls)
Create a CompositeCollection with colls as the initial list of composited collections.

Method Summary

boolean	add(java.lang.Object obj) Adds an object to the collection, throwing UnsupportedOperationException unless a CollectionMutator strategy is specified.
boolean	addAll(java.util.Collection coll) Adds a collection of elements to this collection, throwing UnsupportedOperationException unless a CollectionMutator strategy is specified.
void	addComposited(java.util.Collection c) Add an additional collection to this composite.
void	addComposited(java.util.Collection[] comps) Add these Collections to the list of collections in this composite
void	addComposited(java.util.Collection c, java.util.Collection d) Add two additional collections to this composite.
void	clear() Removes all of the elements from this collection .
boolean	contains(java.lang.Object obj) Checks whether this composite collection contains the object.
boolean	containsAll(java.util.Collection coll) Checks whether this composite contains all the elements in the specified collection.
java.util.Collection	getCollections() Gets the collections being decorated.
boolean	isEmpty() Checks whether this composite collection is empty.
java.util.Iterator	iterator() Gets an iterator over all the collections in this composite.
boolean	remove(java.lang.Object obj) Removes an object from the collection, throwing UnsupportedOperationException unless a CollectionMutator strategy is specified.
boolean	removeAll(java.util.Collection coll) Removes the elements in the specified collection from this composite collection.
void	removeComposited(java.util.Collection coll) Removes a collection from the those being decorated in this composite.
boolean	retainAll(java.util.Collection coll) Retains all the elements in the specified collection in this composite collection, removing all others.
void	setMutator(CompositeCollection.CollectionMutator mutator) Specify a CollectionMutator strategy instance to handle changes.
int	size() Gets the size of this composite collection.
java.lang.Object[]	toArray() Returns an array containing all of the elements in this composite.
java.lang.Object[]	toArray(java.lang.Object[] array) Returns an object array, populating the supplied array if possible.
java.util.Collection	toCollection() Returns a new collection containing all of the elements

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

equals, hashCode

Field Detail

mutator

protected CompositeCollection.CollectionMutator mutator

CollectionMutator to handle changes to the collection

all

protected java.util.Collection[] all

Collections in the composite

Constructor Detail

CompositeCollection

public CompositeCollection()

Create an empty CompositeCollection.

CompositeCollection

public CompositeCollection(java.util.Collection coll)

Create a Composite Collection with only coll composited.

Parameters:

coll - a collection to decorate

CompositeCollection

public CompositeCollection(java.util.Collection[] colls)

Create a CompositeCollection with colls as the initial list of composited collections.

Parameters:

colls - an array of collections to decorate

Method Detail

size

public int size()

Gets the size of this composite collection.

This implementation calls size() on each collection.

Specified by:

size in interface java.util.Collection

Returns:

total number of elements in all contained containers

isEmpty

public boolean isEmpty()

Checks whether this composite collection is empty.

This implementation calls isEmpty() on each collection.

Specified by:

isEmpty in interface java.util.Collection

Returns:

true if all of the contained collections are empty

contains

public boolean contains(java.lang.Object obj)

Checks whether this composite collection contains the object.

This implementation calls contains() on each collection.

Specified by:

contains in interface java.util.Collection

Parameters:

obj - the object to search for

Returns:

true if obj is contained in any of the contained collections

iterator

public java.util.Iterator iterator()

Gets an iterator over all the collections in this composite.

This implementation uses an IteratorChain.

Specified by:

iterator in interface java.lang.Iterable

Specified by:

iterator in interface java.util.Collection

Returns:

an IteratorChain instance which supports remove(). Iteration occurs over contained collections in the order they were added, but this behavior should not be relied upon.

See Also:

IteratorChain

toArray

public java.lang.Object[] toArray()

Returns an array containing all of the elements in this composite.

Specified by:

toArray in interface java.util.Collection

Returns:

an object array of all the elements in the collection

toArray

public java.lang.Object[] toArray(java.lang.Object[] array)

Returns an object array, populating the supplied array if possible. See Collection interface for full details.

Specified by:

toArray in interface java.util.Collection

Parameters:

array - the array to use, populating if possible

Returns:

an array of all the elements in the collection

add

public boolean add(java.lang.Object obj)

Adds an object to the collection, throwing UnsupportedOperationException unless a CollectionMutator strategy is specified.

Specified by:

add in interface java.util.Collection

Parameters:

obj - the object to add

Returns:

true if the collection was modified

Throws:

java.lang.UnsupportedOperationException - if CollectionMutator hasn't been set

java.lang.UnsupportedOperationException - if add is unsupported

java.lang.ClassCastException - if the object cannot be added due to its type

java.lang.NullPointerException - if the object cannot be added because its null

java.lang.IllegalArgumentException - if the object cannot be added

remove

public boolean remove(java.lang.Object obj)

Removes an object from the collection, throwing UnsupportedOperationException unless a CollectionMutator strategy is specified.

Specified by:

remove in interface java.util.Collection

Parameters:

obj - the object being removed

Returns:

true if the collection is changed

Throws:

java.lang.UnsupportedOperationException - if removed is unsupported

java.lang.ClassCastException - if the object cannot be removed due to its type

java.lang.NullPointerException - if the object cannot be removed because its null

java.lang.IllegalArgumentException - if the object cannot be removed

containsAll

public boolean containsAll(java.util.Collection coll)

Checks whether this composite contains all the elements in the specified collection.

This implementation calls contains() for each element in the specified collection.

Specified by:

containsAll in interface java.util.Collection

Parameters:

coll - the collection to check for

Returns:

true if all elements contained

addAll

public boolean addAll(java.util.Collection coll)

Adds a collection of elements to this collection, throwing UnsupportedOperationException unless a CollectionMutator strategy is specified.

Specified by:

addAll in interface java.util.Collection

Parameters:

coll - the collection to add

Returns:

true if the collection was modified

Throws:

java.lang.UnsupportedOperationException - if CollectionMutator hasn't been set

java.lang.UnsupportedOperationException - if add is unsupported

java.lang.ClassCastException - if the object cannot be added due to its type

java.lang.NullPointerException - if the object cannot be added because its null

java.lang.IllegalArgumentException - if the object cannot be added

removeAll

public boolean removeAll(java.util.Collection coll)

Removes the elements in the specified collection from this composite collection.

This implementation calls removeAll on each collection.

Specified by:

removeAll in interface java.util.Collection

Parameters:

coll - the collection to remove

Returns:

true if the collection was modified

Throws:

java.lang.UnsupportedOperationException - if removeAll is unsupported

retainAll

public boolean retainAll(java.util.Collection coll)

Retains all the elements in the specified collection in this composite collection, removing all others.

This implementation calls retainAll() on each collection.

Specified by:

retainAll in interface java.util.Collection

Parameters:

coll - the collection to remove

Returns:

true if the collection was modified

Throws:

java.lang.UnsupportedOperationException - if retainAll is unsupported

clear

public void clear()

Removes all of the elements from this collection .

This implementation calls clear() on each collection.

Specified by:

clear in interface java.util.Collection

Throws:

java.lang.UnsupportedOperationException - if clear is unsupported

setMutator

public void setMutator(CompositeCollection.CollectionMutator mutator)

Specify a CollectionMutator strategy instance to handle changes.

Parameters:

mutator - the mutator to use

addComposited

public void addComposited(java.util.Collection[] comps)

Add these Collections to the list of collections in this composite

Parameters:

comps - Collections to be appended to the composite

addComposited

public void addComposited(java.util.Collection c)

Add an additional collection to this composite.

Parameters:

c - the collection to add

addComposited

public void addComposited(java.util.Collection c,
                          java.util.Collection d)

Add two additional collections to this composite.

Parameters:

c - the first collection to add

d - the second collection to add

removeComposited

public void removeComposited(java.util.Collection coll)

Removes a collection from the those being decorated in this composite.

Parameters:

coll - collection to be removed

toCollection

public java.util.Collection toCollection()

Returns a new collection containing all of the elements

Returns:

A new ArrayList containing all of the elements in this composite. The new collection is not backed by this composite.

getCollections

public java.util.Collection getCollections()

Gets the collections being decorated.

Returns:

Unmodifiable collection of all collections in this composite.