@GwtCompatible(serializable=true,
emulated=true)
public final class HashMultiset<E>
extends java.util.AbstractCollection<E>
HashMap.Multiset.Entry<E>| Modifier and Type | Method and Description |
|---|---|
boolean |
add(E element)
Adds a single occurrence of the specified element to this multiset.
|
int |
add(E element,
int occurrences)
Adds a number of occurrences of an element to this multiset.
|
boolean |
addAll(java.util.Collection<? extends E> elementsToAdd) |
void |
clear() |
boolean |
contains(java.lang.Object element)
Determines whether this multiset contains the specified element.
|
int |
count(java.lang.Object element)
Returns the number of occurrences of an element in this multiset (the
count of the element).
|
static <E> HashMultiset<E> |
create()
Creates a new, empty
HashMultiset using the default initial
capacity. |
static <E> HashMultiset<E> |
create(int distinctElements)
Creates a new, empty
HashMultiset with the specified expected
number of distinct elements. |
static <E> HashMultiset<E> |
create(java.lang.Iterable<? extends E> elements)
Creates a new
HashMultiset containing the specified elements. |
java.util.Set<E> |
elementSet()
Returns the set of distinct elements contained in this multiset.
|
java.util.Set<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(java.lang.Object object)
Compares the specified object with this multiset for equality.
|
int |
hashCode()
Returns the hash code for this multiset.
|
boolean |
isEmpty() |
java.util.Iterator<E> |
iterator() |
boolean |
remove(java.lang.Object element)
Removes a single occurrence of the specified element from this
multiset, if present.
|
int |
remove(java.lang.Object element,
int occurrences)
Removes a number of occurrences of the specified element from this
multiset.
|
boolean |
removeAll(java.util.Collection<?> elementsToRemove) |
boolean |
retainAll(java.util.Collection<?> elementsToRetain) |
int |
setCount(E element,
int count)
Adds or removes the necessary occurrences of an element such that the
element attains the desired count.
|
boolean |
setCount(E element,
int oldCount,
int newCount)
Conditionally sets the count of an element to a new value, as described in
Multiset.setCount(Object, int), provided that the element has the expected
current count. |
int |
size() |
java.lang.String |
toString() |
clone, finalize, getClass, notify, notifyAll, wait, wait, waitcontainsAllpublic static <E> HashMultiset<E> create()
HashMultiset using the default initial
capacity.public static <E> HashMultiset<E> create(int distinctElements)
HashMultiset with the specified expected
number of distinct elements.distinctElements - the expected number of distinct elementsjava.lang.IllegalArgumentException - if distinctElements is negativepublic static <E> HashMultiset<E> create(java.lang.Iterable<? extends E> elements)
HashMultiset containing the specified elements.
This implementation is highly efficient when elements is itself
a Multiset.
elements - the elements that the multiset should containpublic java.util.Set<Multiset.Entry<E>> entrySet()
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.
Invoking Multiset.Entry.getCount() on an entry in the returned
set always returns the current count of that element in the multiset, as
opposed to the count at the time the entry was retrieved.
public void clear()
clear in interface java.util.Collection<E>public int size()
size in interface java.util.Collection<E>public java.util.Iterator<E> iterator()
MultisetElements that occur multiple times in the multiset will appear multiple times in this iterator, though not necessarily sequentially.
public int count(@Nullable
java.lang.Object element)
MultisetObject.equals(java.lang.Object)-based
multiset, this gives the same result as Collections.frequency(java.util.Collection<?>, java.lang.Object)
(which would presumably perform more poorly).
Note: the utility method Iterables.frequency(java.lang.Iterable<?>, java.lang.Object) generalizes
this operation; it correctly delegates to this method when dealing with a
multiset, but it can also accept any other iterable type.
public int add(@Nullable
E element,
int occurrences)
occurrences == 1, this method has the identical effect to Multiset.add(Object). This method is functionally equivalent (except in the case
of overflow) to the call addAll(Collections.nCopies(element,
occurrences)), which would presumably perform much more poorly.add in interface Multiset<E>element - the element to add occurrences of; may be null only if
explicitly allowed by the implementationoccurrences - the number of occurrences of the element to add. May be
zero, in which case no change will be made.java.lang.IllegalArgumentException - if the call would result in more than
Integer.MAX_VALUE occurrences of element in this
multiset.public int remove(@Nullable
java.lang.Object element,
int occurrences)
Multisetoccurrences == 1, this is functionally equivalent to the call
remove(element).remove in interface Multiset<E>element - the element to conditionally remove occurrences ofoccurrences - the number of occurrences of the element to remove. May
be zero, in which case no change will be made.public int setCount(@Nullable
E element,
int count)
MultisetsetCount in interface Multiset<E>element - the element to add or remove occurrences of; may be null
only if explicitly allowed by the implementationcount - the desired count of the element in this multisetpublic boolean isEmpty()
isEmpty in interface java.util.Collection<E>isEmpty in class java.util.AbstractCollection<E>public boolean contains(@Nullable
java.lang.Object element)
MultisetThis 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.
public boolean add(@Nullable
E element)
MultisetThis method refines Collection.add(E), which only ensures
the presence of the element, to further specify that a successful call must
always increment the count of the element, and the overall size of the
collection, by one.
add in interface java.util.Collection<E>add in interface Multiset<E>add in class java.util.AbstractCollection<E>element - the element to add one occurrence of; may be null only if
explicitly allowed by the implementationtrue always, since this call is required to modify the
multiset, unlike other Collection typespublic boolean remove(@Nullable
java.lang.Object element)
MultisetThis method refines Collection.remove(java.lang.Object) to further specify that it
may not throw an exception in response to element being null
or of the wrong type.
public boolean setCount(@Nullable
E element,
int oldCount,
int newCount)
MultisetMultiset.setCount(Object, int), provided that the element has the expected
current count. If the current count is not oldCount, no change is
made.setCount in interface Multiset<E>element - the element to conditionally set the count of; may be null
only if explicitly allowed by the implementationoldCount - the expected present count of the element in this multisetnewCount - the desired count of the element in this multisettrue if the condition for modification was met. This
implies that the multiset was indeed modified, unless
oldCount == newCount.public boolean addAll(java.util.Collection<? extends E> elementsToAdd)
This implementation is highly efficient when elementsToAdd
is itself a Multiset.
addAll in interface java.util.Collection<E>addAll in class java.util.AbstractCollection<E>public boolean removeAll(java.util.Collection<?> elementsToRemove)
MultisetNote: This method ignores how often any element might appear in
c, and only cares whether or not an element appears at all.
If you wish to remove one occurrence in this multiset for every occurrence
in c, see Multisets.removeOccurrences(Multiset, Multiset).
This method refines Collection.removeAll(java.util.Collection<?>) to further specify that
it may not throw an exception in response to any of elements
being null or of the wrong type.
public boolean retainAll(java.util.Collection<?> elementsToRetain)
MultisetNote: This method ignores how often any element might appear in
c, and only cares whether or not an element appears at all.
If you wish to remove one occurrence in this multiset for every occurrence
in c, see Multisets.retainOccurrences(Multiset, Multiset).
This method refines Collection.retainAll(java.util.Collection<?>) to further specify that
it may not throw an exception in response to any of elements
being null or of the wrong type.
retainAll in interface java.util.Collection<E>retainAll in interface Multiset<E>retainAll in class java.util.AbstractCollection<E>Multisets.retainOccurrences(Multiset, Multiset)public java.util.Set<E> elementSet()
MultisetIf 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().
elementSet in interface Multiset<E>public boolean equals(@Nullable
java.lang.Object object)
true if the given object is also a multiset and contains equal
elements with equal counts, regardless of order.
This implementation returns true if object is a multiset
of the same size and if, for each element, the two multisets have the same
count.
public int hashCode()
((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.
This implementation returns the hash code of Multiset.entrySet().
public java.lang.String toString()
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].
This implementation returns the result of invoking toString on
Multiset.entrySet().