org.apache.cayenne.util.commons

Class CompositeCollection<E>

java.lang.Object

org.apache.cayenne.util.commons.CompositeCollection<E>

All Implemented Interfaces:

Iterable<E>, Collection<E>

public class CompositeCollection<E>
extends Object
implements Collection<E>

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:

4.1 NOTE: this is a simplified and type-safe version of CompositeCollection found in commons-collections v3.2.1

Author:

Brian McCallister, Stephen Colebourne, Phil Steitz

Field Summary

Fields

Modifier and Type	Field and Description
protected ArrayList<Collection<E>>	all Collections in the composite

Constructor Summary

Constructors

Constructor and Description
CompositeCollection() Create an empty CompositeCollection.

Method Summary

Modifier and Type	Method and Description
boolean	add(Object obj) Adds an object to the collection, throwing UnsupportedOperationException unless a CollectionMutator strategy is specified.
boolean	addAll(Collection<? extends E> coll) Adds a collection of elements to this collection, throwing UnsupportedOperationException unless a CollectionMutator strategy is specified.
void	addComposited(Collection<E> c) Add an 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<Collection<E>>	getCollections() Gets the collections being decorated.
boolean	isEmpty() Checks whether this composite collection is empty.
Iterator<E>	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<E> coll) Removes a collection from the those being decorated in this composite.
boolean	retainAll(Collection<?> coll) Retains all the elements in the specified collection in this composite collection, removing all others.
int	size() Gets the size of this composite collection.
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.

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, parallelStream, removeIf, spliterator, stream

Methods inherited from interface java.lang.Iterable

forEach

Field Detail

all

protected ArrayList<Collection<E>> all

Collections in the composite

Constructor Detail

CompositeCollection

public CompositeCollection()

Create an empty CompositeCollection.

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 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 Collection<E>

Returns:

true if all of the contained collections are empty

contains

public boolean contains(Object obj)

Checks whether this composite collection contains the object.

This implementation calls contains() on each collection.

Specified by:

contains in interface Collection<E>

Parameters:

obj - the object to search for

Returns:

true if obj is contained in any of the contained collections

iterator

public Iterator<E> iterator()

Gets an iterator over all the collections in this composite.

This implementation uses an IteratorChain.

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface 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 Object[] toArray()

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

Specified by:

toArray in interface 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 Collection<E>

Parameters:

array - the array to use, populating if possible

Returns:

an array of all the elements in the collection

add

public boolean add(Object obj)

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

Specified by:

add in interface Collection<E>

Parameters:

obj - the object to add

Returns:

true if the collection was modified

Throws:

UnsupportedOperationException - if CollectionMutator hasn't been set

UnsupportedOperationException - if add is unsupported

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

NullPointerException - if the object cannot be added because its null

IllegalArgumentException - if the object cannot be added

remove

public boolean remove(Object obj)

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

Specified by:

remove in interface Collection<E>

Parameters:

obj - the object being removed

Returns:

true if the collection is changed

Throws:

UnsupportedOperationException - if removed is unsupported

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

NullPointerException - if the object cannot be removed because its null

IllegalArgumentException - if the object cannot be removed

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.

Specified by:

containsAll in interface Collection<E>

Parameters:

coll - the collection to check for

Returns:

true if all elements contained

addAll

public boolean addAll(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 Collection<E>

Parameters:

coll - the collection to add

Returns:

true if the collection was modified

Throws:

UnsupportedOperationException - if CollectionMutator hasn't been set

UnsupportedOperationException - if add is unsupported

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

NullPointerException - if the object cannot be added because its null

IllegalArgumentException - if the object cannot be added

removeAll

public boolean removeAll(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 Collection<E>

Parameters:

coll - the collection to remove

Returns:

true if the collection was modified

Throws:

UnsupportedOperationException - if removeAll is unsupported

retainAll

public boolean retainAll(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 Collection<E>

Parameters:

coll - the collection to remove

Returns:

true if the collection was modified

Throws:

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 Collection<E>

Throws:

UnsupportedOperationException - if clear is unsupported

addComposited

public void addComposited(Collection<E> c)

Add an additional collection to this composite.

Parameters:

c - the collection to add

removeComposited

public void removeComposited(Collection<E> coll)

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

Parameters:

coll - collection to be removed

getCollections

public Collection<Collection<E>> getCollections()

Gets the collections being decorated.

Returns:

Unmodifiable collection of all collections in this composite.