## com.google.common.collect
Class Multisets

    java.lang.Object
      com.google.common.collect.Multisets

    @GwtCompatible
    public final class Multisets

extends Object

Provides static utility methods for creating and working with `Multiset` instances.

See the Guava User Guide article on `Multisets`.

Since:
  2.0 (imported from Google Collections Library)
Author:
  Kevin Bourrillion, Mike Bostock, Louis Wasserman

Method Summary
`static boolean` `containsOccurrences(Multiset<?> superMultiset, Multiset<?> subMultiset)` Returns `true` if `subMultiset.count(o) <= superMultiset.count(o)` for all `o`.

`static

`<E> ImmutableMultiset<E>`

`

`copyHighestCountFirst(Multiset<E> multiset)`
Returns a copy of `multiset` as an `ImmutableMultiset` whose iteration order is highest count first, with ties broken by the iteration order of the original multiset.

`static

`<E> Multiset.Entry<E>`

`

`immutableEntry(E e, int n)`
Returns an immutable multiset entry with the specified element and count.

`static

`<E> Multiset<E>`

`

`intersection(Multiset<E> multiset1, Multiset<?> multiset2)`
Returns an unmodifiable view of the intersection of two multisets.

`static boolean` `removeOccurrences(Multiset<?> multisetToModify, Multiset<?> occurrencesToRemove)` For each occurrence of an element `e` in `occurrencesToRemove`, removes one occurrence of `e` in `multisetToModify`.
`static boolean` `retainOccurrences(Multiset<?> multisetToModify, Multiset<?> multisetToRetain)` Modifies `multisetToModify` so that its count for an element `e` is at most `multisetToRetain.count(e)`.

`static

`<E> Multiset<E>`

`

`unmodifiableMultiset(ImmutableMultiset<E> multiset)`
Deprecated. no need to use this

`static

`<E> Multiset<E>`

`

`unmodifiableMultiset(Multiset<? extends E> multiset)`
Returns an unmodifiable view of the specified multiset.

`static

`<E> SortedMultiset<E>`

`

`unmodifiableSortedMultiset(SortedMultiset<E> sortedMultiset)`
Returns an unmodifiable view of the specified sorted multiset.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Method Detail

### unmodifiableMultiset

    public static <E> Multiset<E> unmodifiableMultiset(Multiset<? extends E> multiset)

  Returns an unmodifiable view of the specified multiset. Query operations on the returned multiset "read through" to the specified multiset, and attempts to modify the returned multiset result in an `UnsupportedOperationException`.

  The returned multiset will be serializable if the specified multiset is serializable.

  Parameters:
    `multiset` - the multiset for which an unmodifiable view is to be generated
  Returns:
    an unmodifiable view of the multiset

### unmodifiableMultiset

    @Deprecated
    public static <E> Multiset<E> unmodifiableMultiset(ImmutableMultiset<E> multiset)

  Deprecated. no need to use this

  Simply returns its argument.

  Since:
    10.0

### unmodifiableSortedMultiset

    @Beta
    public static <E> SortedMultiset<E> unmodifiableSortedMultiset(SortedMultiset<E> sortedMultiset)

  Returns an unmodifiable view of the specified sorted multiset. Query operations on the returned multiset "read through" to the specified multiset, and attempts to modify the returned multiset result in an `UnsupportedOperationException`.

  The returned multiset will be serializable if the specified multiset is serializable.

  Parameters:
    `sortedMultiset` - the sorted multiset for which an unmodifiable view is to be generated
  Returns:
    an unmodifiable view of the multiset
  Since:
    11.0

### immutableEntry

    public static <E> Multiset.Entry<E> immutableEntry(@Nullable
                                                       E e,
                                                       int n)

  Returns an immutable multiset entry with the specified element and count. The entry will be serializable if `e` is.

  Parameters:
    `e` - the element to be associated with the returned entry
    `n` - the count to be associated with the returned entry
  Throws:
    `IllegalArgumentException` - if `n` is negative

### intersection

    public static <E> Multiset<E> intersection(Multiset<E> multiset1,
                                               Multiset<?> multiset2)

  Returns an unmodifiable view of the intersection of two multisets. An element's count in the multiset is the smaller of its counts in the two backing multisets. The iteration order of the returned multiset matches the element set of `multiset1`, with repeated occurrences of the same element appearing consecutively.

  Results are undefined if `multiset1` and `multiset2` are based on different equivalence relations (as `HashMultiset` and `TreeMultiset` are).

  Since:
    2.0

### containsOccurrences

    public static boolean containsOccurrences(Multiset<?> superMultiset,
                                              Multiset<?> subMultiset)

  Returns `true` if `subMultiset.count(o) <= superMultiset.count(o)` for all `o`.

  Since:
    10.0

### retainOccurrences

    public static boolean retainOccurrences(Multiset<?> multisetToModify,
                                            Multiset<?> multisetToRetain)

  Modifies `multisetToModify` so that its count for an element `e` is at most `multisetToRetain.count(e)`.

  To be precise, `multisetToModify.count(e)` is set to `Math.min(multisetToModify.count(e), multisetToRetain.count(e))`. This is similar to `intersection` `(multisetToModify, multisetToRetain)`, but mutates `multisetToModify` instead of returning a view.

  In contrast, `multisetToModify.retainAll(multisetToRetain)` keeps all occurrences of elements that appear at all in `multisetToRetain`, and deletes all occurrences of all other elements.

  Returns:
    `true` if `multisetToModify` was changed as a result of this operation
  Since:
    10.0

### removeOccurrences

    public static boolean removeOccurrences(Multiset<?> multisetToModify,
                                            Multiset<?> occurrencesToRemove)

  For each occurrence of an element `e` in `occurrencesToRemove`, removes one occurrence of `e` in `multisetToModify`.

  Equivalently, this method modifies `multisetToModify` so that `multisetToModify.count(e)` is set to `Math.max(0, multisetToModify.count(e) - occurrencesToRemove.count(e))`.

  This is not the same as `multisetToModify.` `removeAll``(occurrencesToRemove)`, which removes all occurrences of elements that appear in `occurrencesToRemove`. However, this operation is equivalent to, albeit more efficient than, the following:

         for (E e : occurrencesToRemove) {
           multisetToModify.remove(e);
         }

  Returns:
    `true` if `multisetToModify` was changed as a result of this operation
  Since:
    10.0

### copyHighestCountFirst

    @Beta
    public static <E> ImmutableMultiset<E> copyHighestCountFirst(Multiset<E> multiset)

  Returns a copy of `multiset` as an `ImmutableMultiset` whose iteration order is highest count first, with ties broken by the iteration order of the original multiset.

  Since:
    11.0

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