org.apache.commons.collections4.collection

Class CompositeCollection<E>

java.lang.Object

org.apache.commons.collections4.collection.CompositeCollection<E>

Type Parameters:

E - the type of the elements in the collection

All Implemented Interfaces:

java.io.Serializable, java.lang.Iterable<E>, java.util.Collection<E>

public class CompositeCollection<E>
extends java.lang.Object
implements java.util.Collection<E>, java.io.Serializable

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:

3.0

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	CompositeCollection.CollectionMutator<E> Pluggable strategy to handle changes to the composite.

Constructor Summary

Constructors

Constructor and Description
CompositeCollection() Create an empty CompositeCollection.
CompositeCollection(java.util.Collection<E>... compositeCollections) Create a Composite Collection with an array of collections.
CompositeCollection(java.util.Collection<E> compositeCollection) Create a Composite Collection with one collection.
CompositeCollection(java.util.Collection<E> compositeCollection1, java.util.Collection<E> compositeCollection2) Create a Composite Collection with two collections.

Method Summary

Modifier and Type	Method and Description
boolean	add(E obj) Adds an object to the collection, throwing UnsupportedOperationException unless a CollectionMutator strategy is specified.
boolean	addAll(java.util.Collection<? extends E> coll) Adds a collection of elements to this collection, throwing UnsupportedOperationException unless a CollectionMutator strategy is specified.
void	addComposited(java.util.Collection<E>... compositeCollections) Add these Collections to the list of collections in this composite
void	addComposited(java.util.Collection<E> compositeCollection) Add these Collections to the list of collections in this composite
void	addComposited(java.util.Collection<E> compositeCollection1, java.util.Collection<E> compositeCollection2) Add these Collections to the list of collections in 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.List<java.util.Collection<E>>	getCollections() Gets the collections being decorated.
boolean	isEmpty() Checks whether this composite collection is empty.
java.util.Iterator<E>	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<E> coll) Removes a collection from the those being decorated in this composite.
boolean	removeIf(java.util.function.Predicate<? super E> filter) Removes all of the elements of this collection that satisfy the given predicate from this composite collection.
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<E> 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.
<T> T[]	toArray(T[] array) Returns an object array, populating the supplied array if possible.
java.util.Collection<E>	toCollection() Returns a new collection containing all of the elements

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

equals, hashCode, parallelStream, spliterator, stream

Methods inherited from interface java.lang.Iterable

forEach

Constructor Detail

CompositeCollection

public CompositeCollection()

Create an empty CompositeCollection.

CompositeCollection

public CompositeCollection(java.util.Collection<E> compositeCollection)

Create a Composite Collection with one collection.

Parameters:

compositeCollection - the Collection to be appended to the composite

CompositeCollection

public CompositeCollection(java.util.Collection<E> compositeCollection1,
                           java.util.Collection<E> compositeCollection2)

Create a Composite Collection with two collections.

Parameters:

compositeCollection1 - the Collection to be appended to the composite

compositeCollection2 - the Collection to be appended to the composite

CompositeCollection

public CompositeCollection(java.util.Collection<E>... compositeCollections)

Create a Composite Collection with an array of collections.

Parameters:

compositeCollections - the collections to composite

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<E>

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<E>

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<E>

Parameters:

obj - the object to search for

Returns:

true if obj is contained in any of the contained collections

iterator

public java.util.Iterator<E> iterator()

Gets an iterator over all the collections in this composite.

This implementation uses an IteratorChain.

Specified by:

iterator in interface java.lang.Iterable<E>

Specified by:

iterator in interface java.util.Collection<E>

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<E>

Returns:

an object array of all the elements in the collection

toArray

public <T> T[] toArray(T[] 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<E>

Type Parameters:

T - the type of the elements in the collection

Parameters:

array - the array to use, populating if possible

Returns:

an array of all the elements in the collection

add

public boolean add(E obj)

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

Specified by:

add in interface java.util.Collection<E>

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<E>

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<E>

Parameters:

coll - the collection to check for

Returns:

true if all elements contained

addAll

public boolean addAll(java.util.Collection<? extends E> 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<E>

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<E>

Parameters:

coll - the collection to remove

Returns:

true if the collection was modified

Throws:

java.lang.UnsupportedOperationException - if removeAll is unsupported

removeIf

public boolean removeIf(java.util.function.Predicate<? super E> filter)

Removes all of the elements of this collection that satisfy the given predicate from this composite collection.

This implementation calls removeIf on each collection.

Specified by:

removeIf in interface java.util.Collection<E>

Parameters:

filter - a predicate which returns true for elements to be removed

Returns:

true if the collection was modified

Throws:

java.lang.UnsupportedOperationException - if removeIf is unsupported

Since:

4.4

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<E>

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<E>

Throws:

java.lang.UnsupportedOperationException - if clear is unsupported

setMutator

public void setMutator(CompositeCollection.CollectionMutator<E> mutator)

Specify a CollectionMutator strategy instance to handle changes.

Parameters:

mutator - the mutator to use

addComposited

public void addComposited(java.util.Collection<E> compositeCollection)

Add these Collections to the list of collections in this composite

Parameters:

compositeCollection - the Collection to be appended to the composite

addComposited

public void addComposited(java.util.Collection<E> compositeCollection1,
                          java.util.Collection<E> compositeCollection2)

Add these Collections to the list of collections in this composite

Parameters:

compositeCollection1 - the Collection to be appended to the composite

compositeCollection2 - the Collection to be appended to the composite

addComposited

public void addComposited(java.util.Collection<E>... compositeCollections)

Add these Collections to the list of collections in this composite

Parameters:

compositeCollections - the Collections to be appended to the composite

removeComposited

public void removeComposited(java.util.Collection<E> coll)

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

Parameters:

coll - collection to be removed

toCollection

public java.util.Collection<E> 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.List<java.util.Collection<E>> getCollections()

Gets the collections being decorated.

Returns:

Unmodifiable list of all collections in this composite.