CompositeCollection (Apache Commons Collections 4.2 API)

java.lang.Object
- org.apache.commons.collections4.collection.CompositeCollection<E>

Type Parameters:

E - the type of the elements in the collection

All Implemented Interfaces:

Serializable, Iterable<E>, Collection<E>
```
public class CompositeCollection<E>
extends Object
implements Collection<E>, 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.

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(Collection<E>... compositeCollections)` Create a Composite Collection with an array of collections.
`CompositeCollection(Collection<E> compositeCollection)` Create a Composite Collection with one collection.
`CompositeCollection(Collection<E> compositeCollection1, Collection<E> compositeCollection2)` Create a Composite Collection with two collections.

Method Summary

All Methods Instance Methods Concrete Methods
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(Collection<? extends E> coll)` Adds a collection of elements to this collection, throwing UnsupportedOperationException unless a CollectionMutator strategy is specified.
`void`	`addComposited(Collection<E>... compositeCollections)` Add these Collections to the list of collections in this composite
`void`	`addComposited(Collection<E> compositeCollection)` Add these Collections to the list of collections in this composite
`void`	`addComposited(Collection<E> compositeCollection1, 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(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.
`List<Collection<E>>`	`getCollections()` Gets the collections being decorated.
`protected CompositeCollection.CollectionMutator<E>`	`getMutator()` Get the collection mutator to be used for this CompositeCollection.
`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.
`void`	`setMutator(CompositeCollection.CollectionMutator<E> 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.
`<T> T[]`	`toArray(T[] array)` Returns an object array, populating the supplied array if possible.
`Collection<E>`	`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, parallelStream, removeIf, spliterator, stream

Methods inherited from interface java.lang.Iterable
forEach

- Constructor Detail
  - CompositeCollection
```
public CompositeCollection()
```
    Create an empty CompositeCollection.
  - CompositeCollection
```
public CompositeCollection(Collection<E> compositeCollection)
```
    Create a Composite Collection with one collection.
    
    Parameters:
    
    compositeCollection - the Collection to be appended to the composite
  - CompositeCollection
```
public CompositeCollection(Collection<E> compositeCollection1,
                           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(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 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>
    
    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 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
  - 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(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(Collection<E> compositeCollection1,
                          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(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(Collection<E> coll)
```
    Removes a collection from the those being decorated in this composite.
    
    Parameters:
    
    coll - collection to be removed
  - toCollection
```
public 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 List<Collection<E>> getCollections()
```
    Gets the collections being decorated.
    
    Returns:
    
    Unmodifiable list of all collections in this composite.
  - getMutator
```
protected CompositeCollection.CollectionMutator<E> getMutator()
```
    Get the collection mutator to be used for this CompositeCollection.
    
    Returns:
    
    CollectionMutator<E>

Class CompositeCollection<E>

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Collection

Methods inherited from interface java.lang.Iterable

Constructor Detail

CompositeCollection

CompositeCollection

CompositeCollection

CompositeCollection

Method Detail

size

isEmpty

contains

iterator

toArray

toArray

add

remove

containsAll

addAll

removeAll

retainAll

clear

setMutator

addComposited

addComposited

addComposited

removeComposited

toCollection

getCollections

getMutator