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org.apache.commons.collections.collection

Class CompositeCollection

java.lang.Object
|
+--org.apache.commons.collections.collection.CompositeCollection

All Implemented Interfaces:
Collection

Known Direct Subclasses:
CompositeSet


public class CompositeCollection
extends java.lang.Object
implements 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
Authors:
Brian McCallister
Stephen Colebourne
Phil Steitz

Field Summary

Collection[]

all

Collections in the composite

CompositeCollection.CollectionMutator

mutator

CollectionMutator to handle changes to the collection

Constructor Summary

CompositeCollection()

Create an empty CompositeCollection.

CompositeCollection(Collection coll)

Create a Composite Collection with only coll composited.

CompositeCollection(Collection[] colls)

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

Method Summary

boolean

add(Object obj)

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

boolean

addAll(Collection coll)

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

void

addComposited(Collection[] comps)

Add these Collections to the list of collections in this composite

void

addComposited(Collection c)

Add an additional collection to this composite.

void

addComposited(Collection c, Collection d)

Add two additional collection to this composite.

void

clear()

Removes all of the elements from this collection .

boolean

contains(Object obj)

Checks whether this composite collection contains the object.

boolean

containsAll(Collection coll)

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

Collection

getCollections()

Gets the collections being decorated.

boolean

isEmpty()

Checks whether this composite collection is empty.

Iterator

iterator()

Gets an iterator over all the collections in this composite.

boolean

remove(Object obj)

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

boolean

removeAll(Collection coll)

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

void

removeComposited(Collection coll)

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

boolean

retainAll(final 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.

Object[]

toArray()

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

Object[]

toArray(Object[] array)

Returns an object array, populating the supplied array if possible.

Collection

toCollection()

Returns a new collection containing all of the elements

Field Details

all

protected Collection[] all

Collections in the composite


mutator

protected CompositeCollection.CollectionMutator mutator

CollectionMutator to handle changes to the collection

Constructor Details

CompositeCollection

public CompositeCollection()

Create an empty CompositeCollection.


CompositeCollection

public CompositeCollection(Collection coll)

Create a Composite Collection with only coll composited.

Parameters:
coll - a collection to decorate

CompositeCollection

public CompositeCollection(Collection[] colls)

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

Parameters:
colls - an array of collections to decorate

Method Details

add

public boolean add(Object obj)

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

Parameters:
obj - the object to add
Returns:
true if the collection was modified
Throws:
- if CollectionMutator hasn't been set
- if add is unsupported
- if the object cannot be added due to its type
- if the object cannot be added because its null
- if the object cannot be added

addAll

public boolean addAll(Collection coll)

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

Parameters:
coll - the collection to add
Returns:
true if the collection was modified
Throws:
- if CollectionMutator hasn't been set
- if add is unsupported
- if the object cannot be added due to its type
- if the object cannot be added because its null
- if the object cannot be added

addComposited

public void addComposited(Collection c, Collection d)

Add two additional collection to this composite.

Parameters:
c
d

addComposited

public void addComposited(Collection c)

Add an additional collection to this composite.

Parameters:
c

addComposited

public void addComposited(Collection[] comps)

Add these Collections to the list of collections in this composite

Parameters:
comps - Collections to be appended to the composite

clear

public void clear()

Removes all of the elements from this collection .

This implementation calls clear() on each collection.

Throws:
- if clear is unsupported

contains

public boolean contains(Object obj)

Checks whether this composite collection contains the object.

This implementation calls contains() on each collection.

Parameters:
obj
Returns:
true if obj is contained in any of the contained collections

containsAll

public boolean containsAll(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.

Parameters:
coll - the collection to check for
Returns:
true if all elements contained

getCollections

public Collection getCollections()

Gets the collections being decorated.

Returns:
Unmodifiable collection of all collections in this composite.

isEmpty

public boolean isEmpty()

Checks whether this composite collection is empty.

This implementation calls isEmpty() on each collection.

Returns:
true if all of the contained collections are empty

iterator

public Iterator iterator()

Gets an iterator over all the collections in this composite.

This implementation uses an IteratorChain.

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

remove

public boolean remove(Object obj)

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

Parameters:
obj - the object being removed
Returns:
true if the collection is changed
Throws:
- if removed is unsupported
- if the object cannot be removed due to its type
- if the object cannot be removed because its null
- if the object cannot be removed

removeAll

public boolean removeAll(Collection coll)

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

This implementation calls removeAll on each collection.

Parameters:
coll - the collection to remove
Returns:
true if the collection was modified
Throws:
- if removeAll is unsupported

removeComposited

public void removeComposited(Collection coll)

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

Parameters:
coll - collection to be removed

retainAll

public boolean retainAll(final Collection coll)

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

This implementation calls retainAll() on each collection.

Parameters:
coll - the collection to remove
Returns:
true if the collection was modified
Throws:
- if retainAll is unsupported

setMutator

public void setMutator(CompositeCollection.CollectionMutator mutator)

Specify a CollectionMutator strategy instance to handle changes.

Parameters:
mutator - the mutator to use

size

public int size()

Gets the size of this composite collection.

This implementation calls size() on each collection.

Returns:
total number of elements in all contained containers

toArray

public Object[] toArray()

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

Returns:
an object array of all the elements in the collection

toArray

public Object[] toArray(Object[] array)

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

Parameters:
array
Returns:
an array of all the elements in the collection

toCollection

public 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.