Package org.apache.commons.collections4.multiset

Class PredicatedMultiSet<E>

java.lang.Object

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

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

org.apache.commons.collections4.multiset.PredicatedMultiSet<E>

Type Parameters:

E - the type held in the multiset

All Implemented Interfaces:

Serializable, Iterable<E>, Collection<E>, MultiSet<E>

public class PredicatedMultiSet<E>
extends PredicatedCollection<E>
implements MultiSet<E>

Decorates another MultiSet to validate that additions match a specified predicate.

This multiset exists to provide validation for the decorated multiset. It is normally created to decorate an empty multiset. If an object cannot be added to the multiset, an IllegalArgumentException is thrown.

One usage would be to ensure that no null entries are added to the multiset.

 MultiSet<E> set =
      PredicatedMultiSet.predicatedMultiSet(new HashMultiSet<E>(),
                                            NotNullPredicate.notNullPredicate());
 

Since:

4.1

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.commons.collections4.collection.PredicatedCollection

PredicatedCollection.Builder<E>

Nested classes/interfaces inherited from interface org.apache.commons.collections4.MultiSet

MultiSet.Entry<E>

Method Summary

Modifier and Type	Method	Description
int	add(E object, int count)	Adds a number of occurrences of the specified object to the MultiSet.
Set<MultiSet.Entry<E>>	entrySet()	Returns a Set of all entries contained in the MultiSet.
boolean	equals(Object object)	Compares this MultiSet to another object.
int	getCount(Object object)	Returns the number of occurrences of the given object currently in the MultiSet.
int	hashCode()	Gets a hash code for the MultiSet compatible with the definition of equals.
static <E> PredicatedMultiSet<E>	predicatedMultiSet(MultiSet<E> multiset, Predicate<? super E> predicate)	Factory method to create a predicated (validating) multiset.
int	remove(Object object, int count)	Removes a number of occurrences of the specified object from the MultiSet.
int	setCount(E object, int count)	Sets the number of occurrences of the specified object in the MultiSet to the given count.
Set<E>	uniqueSet()	Returns a Set of unique elements in the MultiSet.

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

add, addAll, builder, notNullBuilder, predicatedCollection

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

clear, contains, containsAll, isEmpty, iterator, remove, removeAll, removeIf, retainAll, size, toArray, toArray, toString

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Collection

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

Methods inherited from interface java.lang.Iterable

forEach

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

add, containsAll, iterator, remove, removeAll, retainAll, size

Method Detail

predicatedMultiSet

public static <E> PredicatedMultiSet<E> predicatedMultiSet(MultiSet<E> multiset,
                                                           Predicate<? super E> predicate)

Factory method to create a predicated (validating) multiset.

If there are any elements already in the multiset being decorated, they are validated.

Type Parameters:

E - the type of the elements in the multiset

Parameters:

multiset - the multiset to decorate, must not be null

predicate - the predicate to use for validation, must not be null

Returns:

a new predicated MultiSet

Throws:

NullPointerException - if multiset or predicate is null

IllegalArgumentException - if the multiset contains invalid elements

equals

public boolean equals(Object object)

Description copied from interface: MultiSet

Compares this MultiSet to another object.

This MultiSet equals another object if it is also a MultiSet that contains the same number of occurrences of the same elements.

Specified by:

equals in interface Collection<E>

Specified by:

equals in interface MultiSet<E>

Overrides:

equals in class Object

Parameters:

object - the object to compare to

Returns:

true if equal

hashCode

public int hashCode()

Description copied from interface: MultiSet

Gets a hash code for the MultiSet compatible with the definition of equals. The hash code is defined as the sum total of a hash code for each element. The per element hash code is defined as (e==null ? 0 : e.hashCode()) ^ noOccurances).

Specified by:

hashCode in interface Collection<E>

Specified by:

hashCode in interface MultiSet<E>

Overrides:

hashCode in class Object

Returns:

the hash code of the MultiSet

add

public int add(E object,
               int count)

Description copied from interface: MultiSet

Adds a number of occurrences of the specified object to the MultiSet.

If the object is already in the MultiSet.uniqueSet() then increment its count as reported by MultiSet.getCount(Object). Otherwise add it to the MultiSet.uniqueSet() and report its count as occurrences.

Specified by:

add in interface MultiSet<E>

Parameters:

object - the object to add

count - the number of occurrences to add, may be zero, in which case no change is made to the multiset

Returns:

the number of occurrences of the object in the multiset before this operation; possibly zero

remove

public int remove(Object object,
                  int count)

Description copied from interface: MultiSet

Removes a number of occurrences of the specified object from the MultiSet.

If the number of occurrences to remove is greater than the actual number of occurrences in the multiset, the object will be removed from the multiset.

Specified by:

remove in interface MultiSet<E>

Parameters:

object - the object to remove

count - the number of occurrences to remove, may be zero, in which case no change is made to the multiset

Returns:

the number of occurrences of the object in the multiset before the operation; possibly zero

getCount

public int getCount(Object object)

Description copied from interface: MultiSet

Returns the number of occurrences of the given object currently in the MultiSet. If the object does not exist in the multiset, return 0.

Specified by:

getCount in interface MultiSet<E>

Parameters:

object - the object to search for

Returns:

the number of occurrences of the object, zero if not found

setCount

public int setCount(E object,
                    int count)

Description copied from interface: MultiSet

Sets the number of occurrences of the specified object in the MultiSet to the given count.

If the provided count is zero, the object will be removed from the MultiSet.uniqueSet().

Specified by:

setCount in interface MultiSet<E>

Parameters:

object - the object to update

count - the number of occurrences of the object

Returns:

the number of occurrences of the object before this operation, zero if the object was not contained in the multiset

uniqueSet

public Set<E> uniqueSet()

Description copied from interface: MultiSet

Returns a Set of unique elements in the MultiSet.

Uniqueness constraints are the same as those in Set.

The returned set is backed by this multiset, so any change to either is immediately reflected in the other. Only removal operations are supported, in which case all occurrences of the element are removed from the backing multiset.

Specified by:

uniqueSet in interface MultiSet<E>

Returns:

the Set of unique MultiSet elements

entrySet

public Set<MultiSet.Entry<E>> entrySet()

Description copied from interface: MultiSet

Returns a Set of all entries contained in the MultiSet.

The returned set is backed by this multiset, so any change to either is immediately reflected in the other.

Specified by:

entrySet in interface MultiSet<E>

Returns:

the Set of MultiSet entries