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java.lang.Object java.util.AbstractCollection<E> com.google.common.collect.ConcurrentHashMultiset<E>
public final class ConcurrentHashMultiset<E>
A multiset that supports concurrent modifications and that provides atomic
versions of most Multiset
operations (exceptions where noted). Null
elements are not supported.
Nested Class Summary |
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Nested classes/interfaces inherited from interface com.google.common.collect.Multiset |
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Multiset.Entry<E> |
Method Summary | ||
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boolean |
add(E element)
Adds a single occurrence of the specified element to this multiset. |
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int |
add(E element,
int occurrences)
Adds a number of occurrences of the specified element to this multiset. |
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boolean |
addAll(Collection<? extends E> elementsToAdd)
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void |
clear()
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boolean |
contains(Object element)
Determines whether this multiset contains the specified element. |
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boolean |
containsAll(Collection<?> elements)
Returns true if this multiset contains at least one occurrence of
each element in the specified collection. |
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int |
count(Object element)
Returns the number of occurrences of element in this multiset. |
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static
|
create()
Creates a new, empty ConcurrentHashMultiset using the default
initial capacity, load factor, and concurrency settings. |
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static
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create(Iterable<? extends E> elements)
Creates a new ConcurrentHashMultiset containing the specified
elements, using the default initial capacity, load factor, and concurrency
settings. |
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Set<E> |
elementSet()
Returns the set of distinct elements contained in this multiset. |
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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. |
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boolean |
equals(Object object)
Compares the specified object with this multiset for equality. |
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int |
hashCode()
Returns the hash code for this multiset. |
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boolean |
isEmpty()
|
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Iterator<E> |
iterator()
|
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boolean |
remove(Object element)
Removes a single occurrence of the specified element from this multiset, if present. |
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int |
remove(Object element,
int occurrences)
Removes a number of occurrences of the specified element from this multiset. |
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boolean |
removeAll(Collection<?> elementsToRemove)
|
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boolean |
removeExactly(Object element,
int occurrences)
Removes exactly the specified number of occurrences of element , or
makes no change if this is not possible. |
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boolean |
retainAll(Collection<?> elementsToRetain)
|
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int |
setCount(E element,
int count)
Adds or removes occurrences of element such that the count(java.lang.Object)
of the element becomes count . |
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boolean |
setCount(E element,
int oldCount,
int newCount)
Sets the number of occurrences of element to newCount , but
only if the count is currently oldCount . |
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int |
size()
|
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Object[] |
toArray()
|
|
|
toArray(T[] array)
|
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String |
toString()
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Methods inherited from class java.lang.Object |
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clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Method Detail |
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public static <E> ConcurrentHashMultiset<E> create()
ConcurrentHashMultiset
using the default
initial capacity, load factor, and concurrency settings.
public static <E> ConcurrentHashMultiset<E> create(Iterable<? extends E> elements)
ConcurrentHashMultiset
containing the specified
elements, using the default initial capacity, load factor, and concurrency
settings.
elements
- the elements that the multiset should containpublic int count(@Nullable Object element)
element
in this multiset.
count
in interface Multiset<E>
element
- the element to look for
public int size()
If the data in the multiset is modified by any other threads during this method, it is undefined which (if any) of these modifications will be reflected in the result.
size
in interface Collection<E>
public Object[] toArray()
toArray
in interface Collection<E>
toArray
in class AbstractCollection<E>
public <T> T[] toArray(T[] array)
toArray
in interface Collection<E>
toArray
in class AbstractCollection<E>
public int add(E element, int occurrences)
add
in interface Multiset<E>
element
- the element to addoccurrences
- the number of occurrences to add
IllegalArgumentException
- if occurrences
is negative, or if
the resulting amount would exceed Integer.MAX_VALUE
public int remove(@Nullable Object element, int occurrences)
remove
in interface Multiset<E>
element
- the element whose occurrences should be removedoccurrences
- the number of occurrences of the element to remove
IllegalArgumentException
- if occurrences
is negativepublic boolean removeExactly(@Nullable Object element, int occurrences)
element
, or
makes no change if this is not possible.
This method, in contrast to remove(Object, int)
, has no effect
when the element count is smaller than occurrences
.
element
- the element to removeoccurrences
- the number of occurrences of element
to remove
true
if the removal was possible (including if occurrences
is zero)public int setCount(E element, int count)
element
such that the count(java.lang.Object)
of the element becomes count
.
setCount
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 multiset
element
in the multiset before this call
IllegalArgumentException
- if count
is negativepublic boolean setCount(E element, int oldCount, int newCount)
element
to newCount
, but
only if the count is currently oldCount
. If element
does
not appear in the multiset exactly oldCount
times, no changes will
be 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 multiset
true
if the change was successful. This usually indicates
that the multiset has been modified, but not always: in the case that
oldCount == newCount
, the method will return true
if
the condition was met.
IllegalArgumentException
- if oldCount
or newCount
is
negativepublic Set<Multiset.Entry<E>> entrySet()
Multiset
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.
entrySet
in interface Multiset<E>
public boolean isEmpty()
isEmpty
in interface Collection<E>
isEmpty
in class AbstractCollection<E>
public boolean contains(@Nullable Object element)
Multiset
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.
contains
in interface Multiset<E>
contains
in interface Collection<E>
contains
in class AbstractCollection<E>
element
- the element to check for
true
if this multiset contains at least one occurrence of
the elementpublic Iterator<E> iterator()
Multiset
Elements 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 boolean add(@Nullable E element)
Multiset
This 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 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 implementation
true
always, since this call is required to modify the
multiset, unlike other Collection
typespublic boolean remove(Object element)
Multiset
This 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.
remove
in interface Multiset<E>
remove
in interface Collection<E>
remove
in class AbstractCollection<E>
element
- the element to remove one occurrence of
true
if an occurrence was found and removedpublic boolean containsAll(Collection<?> elements)
Multiset
true
if this multiset contains at least one occurrence of
each element in the specified collection.
This method refines Collection.containsAll(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.
Note: this method does not take into account the occurrence
count of an element in the two collections; it may still return true
even if elements
contains several occurrences of an element
and this multiset contains only one. This is no different than any other
collection type like List
, but it may be unexpected to the user of
a multiset.
containsAll
in interface Multiset<E>
containsAll
in interface Collection<E>
containsAll
in class AbstractCollection<E>
elements
- the collection of elements to be checked for containment in
this multiset
true
if this multiset contains at least one occurrence of
each element contained in elements
public boolean addAll(Collection<? extends E> elementsToAdd)
addAll
in interface Collection<E>
addAll
in class AbstractCollection<E>
public boolean removeAll(Collection<?> elementsToRemove)
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>
public boolean retainAll(Collection<?> elementsToRetain)
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>
public void clear()
clear
in interface Collection<E>
clear
in class AbstractCollection<E>
public Set<E> elementSet()
Multiset
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()
.
elementSet
in interface Multiset<E>
public 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 other
is a multiset
of the same size and if, for each element, the two multisets have the same
count.
equals
in interface Multiset<E>
equals
in interface Collection<E>
equals
in class Object
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()
.
hashCode
in interface Multiset<E>
hashCode
in interface Collection<E>
hashCode
in class Object
public 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>
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