ImmutableMultiset (Guava: Google Core Libraries for Java 22.0 API)

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 and 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>

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and 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 element)` 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,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 com.google.common.collect.Multiset
add, containsAll, count, forEach, forEachEntry, remove, removeAll, retainAll, size, spliterator

Methods inherited from interface java.util.Collection
addAll, clear, isEmpty, parallelStream, removeIf, stream, toArray, toArray

- Method Detail
  - toImmutableMultiset
```
@Beta
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,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.
  - of
```
public static <E> ImmutableMultiset<E> of(E element)
```
    Returns an immutable multiset containing a single element.
    
    Throws:
    
    NullPointerException - if 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 Multiset<E>
    
    Specified by:
    
    iterator in interface Iterable<E>
    
    Specified by:
    
    iterator in interface Collection<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(@Nullable
                        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 Multiset<E>
    
    Specified by:
    
    contains in interface Collection<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
```
@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
```
@Deprecated
public final int remove(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
```
@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
```
@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(@Nullable
                      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 Multiset<E>
    
    Specified by:
    
    equals in interface Collection<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 Multiset<E>
    
    Specified by:
    
    hashCode in interface Collection<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.

Class ImmutableMultiset<E>

Nested Class Summary

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

Method Summary

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

Methods inherited from class java.util.AbstractCollection

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

Method Detail

toImmutableMultiset

toImmutableMultiset

of

of

of

of

of

of

of

copyOf

copyOf

copyOf

iterator

asList

contains

add

remove

setCount

setCount

equals

hashCode

toString

elementSet

entrySet

builder