@GwtCompatible(serializable=true, emulated=true) public final class HashMultiset<E> extends 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(Collection<? extends E> elementsToAdd) |
void |
clear() |
boolean |
contains(@Nullable Object element)
Determines whether this multiset contains the specified element.
|
int |
count(@Nullable 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(Iterable<? extends E> elements)
Creates a new
HashMultiset containing the specified elements. |
Set<E> |
elementSet()
Returns the set of distinct elements contained in this multiset.
|
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(@Nullable Object object)
Compares the specified object with this multiset for equality.
|
void |
forEachEntry(ObjIntConsumer<? super E> action)
Runs the specified action for each distinct element in this multiset, and the number of
occurrences of that element.
|
int |
hashCode()
Returns the hash code for this multiset.
|
boolean |
isEmpty() |
Iterator<E> |
iterator() |
boolean |
remove(@Nullable Object element)
Removes a single occurrence of the specified element from this multiset, if present.
|
int |
remove(@Nullable Object element,
int occurrences)
Removes a number of occurrences of the specified element from this multiset.
|
boolean |
removeAll(Collection<?> elementsToRemove) |
boolean |
retainAll(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()
Returns the total number of all occurrences of all elements in this multiset.
|
String |
toString() |
containsAll, toArray, toArrayclone, finalize, getClass, notify, notifyAll, wait, wait, waitcontainsAll, forEach, spliteratorparallelStream, removeIf, stream, toArray, toArraypublic 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 elementsIllegalArgumentException - if distinctElements is negativepublic static <E> HashMultiset<E> create(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 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 forEachEntry(ObjIntConsumer<? super E> action)
MultisetMultiset implementations, this may be more
efficient than iterating over the Multiset.entrySet() either explicitly or with entrySet().forEach(action).forEachEntry in interface Multiset<E>public void clear()
clear in interface Collection<E>public int size()
MultisetNote: this method does not return the number of distinct elements in the
multiset, which is given by entrySet().size().
size in interface Multiset<E>size in interface Collection<E>size in class AbstractCollection<E>public Iterator<E> iterator()
MultisetElements that occur multiple times in the multiset will appear multiple times in this iterator, though not necessarily sequentially.
iterator in interface Multiset<E>iterator in interface Iterable<E>iterator in interface Collection<E>iterator in class AbstractCollection<E>public int count(@Nullable 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.
@CanIgnoreReturnValue public int add(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.IllegalArgumentException - if the call would result in more than Integer.MAX_VALUE occurrences of element in this multiset.@CanIgnoreReturnValue public int remove(@Nullable 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.@CanIgnoreReturnValue public int setCount(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 Collection<E>isEmpty in class AbstractCollection<E>public boolean contains(@Nullable 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.
contains in interface Multiset<E>contains in interface Collection<E>contains in class AbstractCollection<E>element - the element to check fortrue if this multiset contains at least one occurrence of the element@CanIgnoreReturnValue public final boolean add(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.
To both add the element and obtain the previous count of that element, use add(element, 1) instead.
add in interface Multiset<E>add in interface Collection<E>add in class 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 types@CanIgnoreReturnValue public final boolean remove(@Nullable 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.
To both remove the element and obtain the previous count of that element, use remove(element, 1) instead.
remove in interface Multiset<E>remove in interface Collection<E>remove in class AbstractCollection<E>element - the element to remove one occurrence oftrue if an occurrence was found and removed@CanIgnoreReturnValue public boolean setCount(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.@CanIgnoreReturnValue public final boolean addAll(Collection<? extends E> elementsToAdd)
This implementation is highly efficient when elementsToAdd is itself a Multiset.
addAll in interface Collection<E>addAll in class AbstractCollection<E>@CanIgnoreReturnValue public final boolean removeAll(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.
removeAll in interface Multiset<E>removeAll in interface Collection<E>removeAll in class AbstractCollection<E>@CanIgnoreReturnValue public final boolean retainAll(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 Multiset<E>retainAll in interface Collection<E>retainAll in class AbstractCollection<E>Multisets.retainOccurrences(Multiset, Multiset)public 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 final boolean equals(@Nullable 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 final 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 final 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().
toString in interface Multiset<E>toString in class AbstractCollection<E>Copyright © 2010–2019. All rights reserved.