Package com.google.common.collect

Class ImmutableMultiset<E>

java.lang.Object

java.util.AbstractCollection<E>

com.google.common.collect.ImmutableCollection<E>

com.google.common.collect.ImmutableMultiset<E>

All Implemented Interfaces:

Multiset<E>, Serializable, Iterable<E>, Collection<E>

Direct Known Subclasses:

ImmutableSortedMultiset

@GwtCompatible(serializable=true,
               emulated=true)
public abstract class ImmutableMultiset<E>
extends ImmutableCollection<E>
implements Multiset<E>

A Multiset whose contents will never change, with many other important properties detailed at ImmutableCollection.

Grouped iteration. In all current implementations, duplicate elements always appear consecutively when iterating. Elements iterate in order by the first appearance of that element when the multiset was created.

See the Guava User Guide article on immutable collections.

Since:

2.0

Author:

Jared Levy, Louis Wasserman

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ImmutableMultiset.Builder<E>	A builder for creating immutable multiset instances, especially public static final multisets ("constant multisets").

Nested classes/interfaces inherited from interface com.google.common.collect.Multiset

Multiset.Entry<E extends @Nullable Object>

Method Summary

Modifier and Type	Method	Description
int	add(E element, int occurrences)	Deprecated. Unsupported operation.
ImmutableList<E>	asList()	Returns an ImmutableList containing the same elements, in the same order, as this collection.
static <E> ImmutableMultiset.Builder<E>	builder()	Returns a new builder.
boolean	contains(Object object)	Determines whether this multiset contains the specified element.
static <E> ImmutableMultiset<E>	copyOf(E[] elements)	Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.
static <E> ImmutableMultiset<E>	copyOf(Iterable<? extends E> elements)	Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.
static <E> ImmutableMultiset<E>	copyOf(Iterator<? extends E> elements)	Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.
abstract ImmutableSet<E>	elementSet()	Returns the set of distinct elements contained in this multiset.
ImmutableSet<Multiset.Entry<E>>	entrySet()	Returns a view of the contents of this multiset, grouped into Multiset.Entry instances, each providing an element of the multiset and the count of that element.
boolean	equals(Object object)	Compares the specified object with this multiset for equality.
int	hashCode()	Returns the hash code for this multiset.
UnmodifiableIterator<E>	iterator()	Returns an unmodifiable iterator across the elements in this collection.
static <E> ImmutableMultiset<E>	of()	Returns the empty immutable multiset.
static <E> ImmutableMultiset<E>	of(E e1)	Returns an immutable multiset containing a single element.
static <E> ImmutableMultiset<E>	of(E e1, E e2)	Returns an immutable multiset containing the given elements, in order.
static <E> ImmutableMultiset<E>	of(E e1, E e2, E e3)	Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.
static <E> ImmutableMultiset<E>	of(E e1, E e2, E e3, E e4)	Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.
static <E> ImmutableMultiset<E>	of(E e1, E e2, E e3, E e4, E e5)	Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.
static <E> ImmutableMultiset<E>	of(E e1, E e2, E e3, E e4, E e5, E e6, E... others)	Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.
int	remove(Object element, int occurrences)	Deprecated. Unsupported operation.
int	setCount(E element, int count)	Deprecated. Unsupported operation.
boolean	setCount(E element, int oldCount, int newCount)	Deprecated. Unsupported operation.
static <E> Collector<E,?,ImmutableMultiset<E>>	toImmutableMultiset()	Returns a Collector that accumulates the input elements into a new ImmutableMultiset.
static <T extends @Nullable Object,E> Collector<T,?,ImmutableMultiset<E>>	toImmutableMultiset(Function<? super T,? extends E> elementFunction, ToIntFunction<? super T> countFunction)	Returns a Collector that accumulates elements into an ImmutableMultiset whose elements are the result of applying elementFunction to the inputs, with counts equal to the result of applying countFunction to the inputs.
String	toString()

Methods inherited from class com.google.common.collect.ImmutableCollection

add, addAll, clear, remove, removeAll, removeIf, retainAll, spliterator, toArray, toArray

Methods inherited from class java.util.AbstractCollection

containsAll, isEmpty, size

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Collection

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

Methods inherited from interface com.google.common.collect.Multiset

add, containsAll, count, forEach, forEachEntry, remove, removeAll, retainAll, size, spliterator

Method Detail

toImmutableMultiset

public static <E> Collector<E,?,ImmutableMultiset<E>> toImmutableMultiset()

Returns a Collector that accumulates the input elements into a new ImmutableMultiset. Elements iterate in order by the first appearance of that element in encounter order.

Since:

21.0

toImmutableMultiset

public static <T extends @Nullable Object,E> Collector<T,?,ImmutableMultiset<E>> toImmutableMultiset(Function<? super T,? extends E> elementFunction,
                                                                                                                       ToIntFunction<? super T> countFunction)

Returns a Collector that accumulates elements into an ImmutableMultiset whose elements are the result of applying elementFunction to the inputs, with counts equal to the result of applying countFunction to the inputs.

If the mapped elements contain duplicates (according to Object.equals(java.lang.Object)), the first occurrence in encounter order appears in the resulting multiset, with count equal to the sum of the outputs of countFunction.applyAsInt(t) for each t mapped to that element.

Since:

22.0

of

public static <E> ImmutableMultiset<E> of()

Returns the empty immutable multiset.

Performance note: the instance returned is a singleton.

of

public static <E> ImmutableMultiset<E> of(E e1)

Returns an immutable multiset containing a single element.

Throws:

NullPointerException - if the element is null

Since:

6.0 (source-compatible since 2.0)

of

public static <E> ImmutableMultiset<E> of(E e1,
                                          E e2)

Returns an immutable multiset containing the given elements, in order.

Throws:

NullPointerException - if any element is null

Since:

6.0 (source-compatible since 2.0)

of

public static <E> ImmutableMultiset<E> of(E e1,
                                          E e2,
                                          E e3)

Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.

Throws:

NullPointerException - if any element is null

Since:

6.0 (source-compatible since 2.0)

of

public static <E> ImmutableMultiset<E> of(E e1,
                                          E e2,
                                          E e3,
                                          E e4)

Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.

Throws:

NullPointerException - if any element is null

Since:

6.0 (source-compatible since 2.0)

of

public static <E> ImmutableMultiset<E> of(E e1,
                                          E e2,
                                          E e3,
                                          E e4,
                                          E e5)

Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.

Throws:

NullPointerException - if any element is null

Since:

6.0 (source-compatible since 2.0)

of

public static <E> ImmutableMultiset<E> of(E e1,
                                          E e2,
                                          E e3,
                                          E e4,
                                          E e5,
                                          E e6,
                                          E... others)

Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.

Throws:

NullPointerException - if any element is null

Since:

6.0 (source-compatible since 2.0)

copyOf

public static <E> ImmutableMultiset<E> copyOf(E[] elements)

Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.

Throws:

NullPointerException - if any of elements is null

Since:

6.0

copyOf

public static <E> ImmutableMultiset<E> copyOf(Iterable<? extends E> elements)

Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.

Throws:

NullPointerException - if any of elements is null

copyOf

public static <E> ImmutableMultiset<E> copyOf(Iterator<? extends E> elements)

Returns an immutable multiset containing the given elements, in the "grouped iteration order" described in the class documentation.

Throws:

NullPointerException - if any of elements is null

iterator

public UnmodifiableIterator<E> iterator()

Description copied from class: ImmutableCollection

Returns an unmodifiable iterator across the elements in this collection.

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface Multiset<E>

Specified by:

iterator in class ImmutableCollection<E>

asList

public ImmutableList<E> asList()

Description copied from class: ImmutableCollection

Returns an ImmutableList containing the same elements, in the same order, as this collection.

Performance note: in most cases this method can return quickly without actually copying anything. The exact circumstances under which the copy is performed are undefined and subject to change.

Overrides:

asList in class ImmutableCollection<E>

contains

public boolean contains(@CheckForNull
                        Object object)

Description copied from interface: Multiset

Determines whether this multiset contains the specified element.

This method refines Collection.contains(java.lang.Object) to further specify that it may not throw an exception in response to element being null or of the wrong type.

Specified by:

contains in interface Collection<E>

Specified by:

contains in interface Multiset<E>

Specified by:

contains in class ImmutableCollection<E>

Parameters:

object - the element to check for

Returns:

true if this multiset contains at least one occurrence of the element

add

@CanIgnoreReturnValue
@Deprecated
public final int add(E element,
                     int occurrences)

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

add in interface Multiset<E>

Parameters:

element - the element to add occurrences of; may be null only if explicitly allowed by the implementation

occurrences - the number of occurrences of the element to add. May be zero, in which case no change will be made.

Returns:

the count of the element before the operation; possibly zero

Throws:

UnsupportedOperationException - always

remove

@CanIgnoreReturnValue
@Deprecated
public final int remove(@CheckForNull
                        Object element,
                        int occurrences)

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

remove in interface Multiset<E>

Parameters:

element - the element to conditionally remove occurrences of

occurrences - the number of occurrences of the element to remove. May be zero, in which case no change will be made.

Returns:

the count of the element before the operation; possibly zero

Throws:

UnsupportedOperationException - always

setCount

@CanIgnoreReturnValue
@Deprecated
public final int setCount(E element,
                          int count)

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

setCount in interface Multiset<E>

Parameters:

element - the element to add or remove occurrences of; may be null only if explicitly allowed by the implementation

count - the desired count of the element in this multiset

Returns:

the count of the element before the operation; possibly zero

Throws:

UnsupportedOperationException - always

setCount

@CanIgnoreReturnValue
@Deprecated
public final boolean setCount(E element,
                              int oldCount,
                              int newCount)

Deprecated.

Unsupported operation.

Guaranteed to throw an exception and leave the collection unmodified.

Specified by:

setCount in interface Multiset<E>

Parameters:

element - the element to conditionally set the count of; may be null only if explicitly allowed by the implementation

oldCount - the expected present count of the element in this multiset

newCount - the desired count of the element in this multiset

Returns:

true if the condition for modification was met. This implies that the multiset was indeed modified, unless oldCount == newCount.

Throws:

UnsupportedOperationException - always

equals

public boolean equals(@CheckForNull
                      Object object)

Description copied from interface: Multiset

Compares the specified object with this multiset for equality. Returns true if the given object is also a multiset and contains equal elements with equal counts, regardless of order.

Specified by:

equals in interface Collection<E>

Specified by:

equals in interface Multiset<E>

Overrides:

equals in class Object

hashCode

public int hashCode()

Description copied from interface: Multiset

Returns the hash code for this multiset. This is defined as the sum of

 ((element == null) ? 0 : element.hashCode()) ^ count(element)
 

over all distinct elements in the multiset. It follows that a multiset and its entry set always have the same hash code.

Specified by:

hashCode in interface Collection<E>

Specified by:

hashCode in interface Multiset<E>

Overrides:

hashCode in class Object

toString

public String toString()

Description copied from interface: Multiset

It is recommended, though not mandatory, that this method return the result of invoking Multiset.toString() on the Multiset.entrySet(), yielding a result such as [a x 3, c, d x 2, e].

Specified by:

toString in interface Multiset<E>

Overrides:

toString in class AbstractCollection<E>

elementSet

public abstract ImmutableSet<E> elementSet()

Description copied from interface: Multiset

Returns the set of distinct elements contained in this multiset. The element set is backed by the same data as the multiset, so any change to either is immediately reflected in the other. The order of the elements in the element set is unspecified.

If the element set supports any removal operations, these necessarily cause all occurrences of the removed element(s) to be removed from the multiset. Implementations are not expected to support the add operations, although this is possible.

A common use for the element set is to find the number of distinct elements in the multiset: elementSet().size().

Specified by:

elementSet in interface Multiset<E>

Returns:

a view of the set of distinct elements in this multiset

Since:

21.0 (present with return type Set since 2.0)

entrySet

public ImmutableSet<Multiset.Entry<E>> entrySet()

Description copied from interface: Multiset

Returns a view of the contents of this multiset, grouped into Multiset.Entry instances, each providing an element of the multiset and the count of that element. This set contains exactly one entry for each distinct element in the multiset (thus it always has the same size as the Multiset.elementSet()). The order of the elements in the element set is unspecified.

The entry set is backed by the same data as the multiset, so any change to either is immediately reflected in the other. However, multiset changes may or may not be reflected in any Entry instances already retrieved from the entry set (this is implementation-dependent). Furthermore, implementations are not required to support modifications to the entry set at all, and the Entry instances themselves don't even have methods for modification. See the specific implementation class for more details on how its entry set handles modifications.

Specified by:

entrySet in interface Multiset<E>

Returns:

a set of entries representing the data of this multiset

builder

public static <E> ImmutableMultiset.Builder<E> builder()

Returns a new builder. The generated builder is equivalent to the builder created by the ImmutableMultiset.Builder constructor.