org.apache.commons.collections4.bag

Class CollectionBag<E>

java.lang.Object

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

org.apache.commons.collections4.bag.AbstractBagDecorator<E>

org.apache.commons.collections4.bag.CollectionBag<E>

Type Parameters:

E - the type of elements in this bag

All Implemented Interfaces:

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

public final class CollectionBag<E>
extends AbstractBagDecorator<E>

Decorates another Bag to comply with the Collection contract.

By decorating an existing Bag instance with a CollectionBag, it can be safely passed on to methods that require Collection types that are fully compliant with the Collection contract.

The method javadoc highlights the differences compared to the original Bag interface.

Since:

4.0

See Also:

Bag, Serialized Form

Constructor Summary

Constructors

Constructor and Description
CollectionBag(Bag<E> bag) Constructor that wraps (not copies).

Method Summary

Modifier and Type	Method and Description
boolean	add(E object) (Change) Adds one copy of the specified object to the Bag.
boolean	add(E object, int count) (Change) Adds count copies of the specified object to the Bag.
boolean	addAll(java.util.Collection<? extends E> coll)
static <E> Bag<E>	collectionBag(Bag<E> bag) Factory method to create a bag that complies to the Collection contract.
boolean	containsAll(java.util.Collection<?> coll) (Change) Returns true if the bag contains all elements in the given collection, not respecting cardinality.
boolean	remove(java.lang.Object object) (Change) Removes the first occurrence of the given object from the bag.
boolean	removeAll(java.util.Collection<?> coll) (Change) Remove all elements represented in the given collection, not respecting cardinality.
boolean	retainAll(java.util.Collection<?> coll) (Change) Remove any members of the bag that are not in the given collection, not respecting cardinality.

Methods inherited from class org.apache.commons.collections4.bag.AbstractBagDecorator

equals, getCount, hashCode, remove, uniqueSet

Methods inherited from class org.apache.commons.collections4.collection.AbstractCollectionDecorator

clear, contains, isEmpty, iterator, size, toArray, toArray, toString

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.commons.collections4.Bag

iterator, size

Methods inherited from interface java.util.Collection

clear, contains, isEmpty, parallelStream, removeIf, spliterator, stream, toArray, toArray

Methods inherited from interface java.lang.Iterable

forEach

Constructor Detail

CollectionBag

public CollectionBag(Bag<E> bag)

Constructor that wraps (not copies).

Parameters:

bag - the bag to decorate, must not be null

Throws:

java.lang.NullPointerException - if bag is null

Method Detail

collectionBag

public static <E> Bag<E> collectionBag(Bag<E> bag)

Factory method to create a bag that complies to the Collection contract.

Type Parameters:

E - the type of the elements in the bag

Parameters:

bag - the bag to decorate, must not be null

Returns:

a Bag that complies to the Collection contract

Throws:

java.lang.NullPointerException - if bag is null

containsAll

public boolean containsAll(java.util.Collection<?> coll)

(Change) Returns true if the bag contains all elements in the given collection, not respecting cardinality. That is, if the given collection coll contains at least one of every object contained in this object.

Specified by:

containsAll in interface java.util.Collection<E>

Specified by:

containsAll in interface Bag<E>

Overrides:

containsAll in class AbstractCollectionDecorator<E>

Parameters:

coll - the collection to check against

Returns:

true if the Bag contains at least one of every object in the collection

add

public boolean add(E object)

(Change) Adds one copy of the specified object to the Bag.

Since this method always increases the size of the bag, it will always return true.

Specified by:

add in interface java.util.Collection<E>

Specified by:

add in interface Bag<E>

Overrides:

add in class AbstractCollectionDecorator<E>

Parameters:

object - the object to add

Returns:

true, always

addAll

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

Specified by:

addAll in interface java.util.Collection<E>

Overrides:

addAll in class AbstractCollectionDecorator<E>

remove

public boolean remove(java.lang.Object object)

(Change) Removes the first occurrence of the given object from the bag.

This will also remove the object from the AbstractBagDecorator.uniqueSet() if the bag contains no occurrence anymore of the object after this operation.

Specified by:

remove in interface java.util.Collection<E>

Specified by:

remove in interface Bag<E>

Overrides:

remove in class AbstractCollectionDecorator<E>

Parameters:

object - the object to remove

Returns:

true if this call changed the collection

removeAll

public boolean removeAll(java.util.Collection<?> coll)

(Change) Remove all elements represented in the given collection, not respecting cardinality. That is, remove all occurrences of every object contained in the given collection.

Specified by:

removeAll in interface java.util.Collection<E>

Specified by:

removeAll in interface Bag<E>

Overrides:

removeAll in class AbstractCollectionDecorator<E>

Parameters:

coll - the collection to remove

Returns:

true if this call changed the collection

retainAll

public boolean retainAll(java.util.Collection<?> coll)

(Change) Remove any members of the bag that are not in the given collection, not respecting cardinality. That is, any object in the given collection coll will be retained in the bag with the same number of copies prior to this operation. All other objects will be completely removed from this bag.

This implementation iterates over the elements of this bag, checking each element in turn to see if it's contained in coll. If it's not contained, it's removed from this bag. As a consequence, it is advised to use a collection type for coll that provides a fast (e.g. O(1)) implementation of Collection.contains(Object).

Specified by:

retainAll in interface java.util.Collection<E>

Specified by:

retainAll in interface Bag<E>

Overrides:

retainAll in class AbstractCollectionDecorator<E>

Parameters:

coll - the collection to retain

Returns:

true if this call changed the collection

add

public boolean add(E object,
                   int count)

(Change) Adds count copies of the specified object to the Bag.

Since this method always increases the size of the bag, it will always return true.

Specified by:

add in interface Bag<E>

Overrides:

add in class AbstractBagDecorator<E>

Parameters:

object - the object to add

count - the number of copies to add

Returns:

true, always