Class ConcurrentHashMultiset<E>
- java.lang.Object
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- java.util.AbstractCollection<E>
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- com.google.common.collect.AbstractMultiset<E>
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- com.google.common.collect.ConcurrentHashMultiset<E>
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- All Implemented Interfaces:
Multiset<E>
,java.io.Serializable
,java.lang.Iterable<E>
,java.util.Collection<E>
@GwtIncompatible public final class ConcurrentHashMultiset<E> extends AbstractMultiset<E> implements java.io.Serializable
A multiset that supports concurrent modifications and that provides atomic versions of mostMultiset
operations (exceptions where noted). Null elements are not supported.See the Guava User Guide article on
Multiset
.- Since:
- 2.0
- See Also:
- Serialized Form
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Nested Class Summary
Nested Classes Modifier and Type Class Description private class
ConcurrentHashMultiset.EntrySet
private static class
ConcurrentHashMultiset.FieldSettersHolder
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Nested classes/interfaces inherited from class com.google.common.collect.AbstractMultiset
AbstractMultiset.ElementSet
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Nested classes/interfaces inherited from interface com.google.common.collect.Multiset
Multiset.Entry<E>
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Field Summary
Fields Modifier and Type Field Description private java.util.concurrent.ConcurrentMap<E,java.util.concurrent.atomic.AtomicInteger>
countMap
The number of occurrences of each element.private static long
serialVersionUID
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Constructor Summary
Constructors Constructor Description ConcurrentHashMultiset(java.util.concurrent.ConcurrentMap<E,java.util.concurrent.atomic.AtomicInteger> countMap)
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method Description int
add(E element, int occurrences)
Adds a number of occurrences of the specified element to this multiset.void
clear()
int
count(java.lang.Object element)
Returns the number of occurrences ofelement
in this multiset.static <E> ConcurrentHashMultiset<E>
create()
Creates a new, emptyConcurrentHashMultiset
using the default initial capacity, load factor, and concurrency settings.static <E> ConcurrentHashMultiset<E>
create(java.lang.Iterable<? extends E> elements)
Creates a newConcurrentHashMultiset
containing the specified elements, using the default initial capacity, load factor, and concurrency settings.static <E> ConcurrentHashMultiset<E>
create(java.util.concurrent.ConcurrentMap<E,java.util.concurrent.atomic.AtomicInteger> countMap)
Creates a new, emptyConcurrentHashMultiset
usingcountMap
as the internal backing map.(package private) java.util.Set<E>
createElementSet()
Creates a new instance of this multiset's element set, which will be returned byAbstractMultiset.elementSet()
.java.util.Set<Multiset.Entry<E>>
createEntrySet()
Deprecated.Internal method, useAbstractMultiset.entrySet()
.(package private) int
distinctElements()
(package private) java.util.Iterator<E>
elementIterator()
(package private) java.util.Iterator<Multiset.Entry<E>>
entryIterator()
boolean
isEmpty()
java.util.Iterator<E>
iterator()
private void
readObject(java.io.ObjectInputStream stream)
int
remove(java.lang.Object element, int occurrences)
Removes a number of occurrences of the specified element from this multiset.boolean
removeExactly(java.lang.Object element, int occurrences)
Removes exactly the specified number of occurrences ofelement
, or makes no change if this is not possible.int
setCount(E element, int count)
Adds or removes occurrences ofelement
such that thecount(java.lang.Object)
of the element becomescount
.boolean
setCount(E element, int expectedOldCount, int newCount)
Sets the number of occurrences ofelement
tonewCount
, but only if the count is currentlyexpectedOldCount
.int
size()
Returns the total number of all occurrences of all elements in this multiset.private java.util.List<E>
snapshot()
java.lang.Object[]
toArray()
<T> T[]
toArray(T[] array)
private void
writeObject(java.io.ObjectOutputStream stream)
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Methods inherited from class com.google.common.collect.AbstractMultiset
add, addAll, contains, elementSet, entrySet, equals, hashCode, remove, removeAll, retainAll, toString
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Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
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Methods inherited from interface com.google.common.collect.Multiset
containsAll, forEach, forEachEntry, spliterator
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Field Detail
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countMap
private final transient java.util.concurrent.ConcurrentMap<E,java.util.concurrent.atomic.AtomicInteger> countMap
The number of occurrences of each element.
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serialVersionUID
private static final long serialVersionUID
- See Also:
- Constant Field Values
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Constructor Detail
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ConcurrentHashMultiset
ConcurrentHashMultiset(java.util.concurrent.ConcurrentMap<E,java.util.concurrent.atomic.AtomicInteger> countMap)
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Method Detail
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create
public static <E> ConcurrentHashMultiset<E> create()
Creates a new, emptyConcurrentHashMultiset
using the default initial capacity, load factor, and concurrency settings.
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create
public static <E> ConcurrentHashMultiset<E> create(java.lang.Iterable<? extends E> elements)
Creates a newConcurrentHashMultiset
containing the specified elements, using the default initial capacity, load factor, and concurrency settings.This implementation is highly efficient when
elements
is itself aMultiset
.- Parameters:
elements
- the elements that the multiset should contain
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create
@Beta public static <E> ConcurrentHashMultiset<E> create(java.util.concurrent.ConcurrentMap<E,java.util.concurrent.atomic.AtomicInteger> countMap)
Creates a new, emptyConcurrentHashMultiset
usingcountMap
as the internal backing map.This instance will assume ownership of
countMap
, and other code should not maintain references to the map or modify it in any way.The returned multiset is serializable if the input map is.
- Parameters:
countMap
- backing map for storing the elements in the multiset and their counts. It must be empty.- Throws:
java.lang.IllegalArgumentException
- ifcountMap
is not empty- Since:
- 20.0
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count
public int count(java.lang.Object element)
Returns the number of occurrences ofelement
in this multiset.
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size
public int size()
Returns the total number of all occurrences of all elements in this multiset.Note: this method does not return the number of distinct elements in the multiset, which is given by
entrySet().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.
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toArray
public java.lang.Object[] toArray()
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toArray
public <T> T[] toArray(T[] array)
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snapshot
private java.util.List<E> snapshot()
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add
public int add(E element, int occurrences)
Adds a number of occurrences of the specified element to this multiset.- Specified by:
add
in interfaceMultiset<E>
- Overrides:
add
in classAbstractMultiset<E>
- Parameters:
element
- the element to addoccurrences
- the number of occurrences to add- Returns:
- the previous count of the element before the operation; possibly zero
- Throws:
java.lang.IllegalArgumentException
- ifoccurrences
is negative, or if the resulting amount would exceedInteger.MAX_VALUE
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remove
public int remove(java.lang.Object element, int occurrences)
Removes a number of occurrences of the specified element from this multiset. If the multiset contains fewer than this number of occurrences to begin with, all occurrences will be removed.- Specified by:
remove
in interfaceMultiset<E>
- Overrides:
remove
in classAbstractMultiset<E>
- Parameters:
element
- the element whose occurrences should be removedoccurrences
- the number of occurrences of the element to remove- Returns:
- the count of the element before the operation; possibly zero
- Throws:
java.lang.IllegalArgumentException
- ifoccurrences
is negative
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removeExactly
public boolean removeExactly(java.lang.Object element, int occurrences)
Removes exactly the specified number of occurrences ofelement
, 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 thanoccurrences
.- Parameters:
element
- the element to removeoccurrences
- the number of occurrences ofelement
to remove- Returns:
true
if the removal was possible (including ifoccurrences
is zero)- Throws:
java.lang.IllegalArgumentException
- ifoccurrences
is negative
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setCount
public int setCount(E element, int count)
Adds or removes occurrences ofelement
such that thecount(java.lang.Object)
of the element becomescount
.- Specified by:
setCount
in interfaceMultiset<E>
- Overrides:
setCount
in classAbstractMultiset<E>
- Parameters:
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- Returns:
- the count of
element
in the multiset before this call - Throws:
java.lang.IllegalArgumentException
- ifcount
is negative
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setCount
public boolean setCount(E element, int expectedOldCount, int newCount)
Sets the number of occurrences ofelement
tonewCount
, but only if the count is currentlyexpectedOldCount
. Ifelement
does not appear in the multiset exactlyexpectedOldCount
times, no changes will be made.- Specified by:
setCount
in interfaceMultiset<E>
- Overrides:
setCount
in classAbstractMultiset<E>
- Parameters:
element
- the element to conditionally set the count of; may be null only if explicitly allowed by the implementationexpectedOldCount
- the expected present count of the element in this multisetnewCount
- the desired count of the element in this multiset- Returns:
true
if the change was successful. This usually indicates that the multiset has been modified, but not always: in the case thatexpectedOldCount == newCount
, the method will returntrue
if the condition was met.- Throws:
java.lang.IllegalArgumentException
- ifexpectedOldCount
ornewCount
is negative
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createElementSet
java.util.Set<E> createElementSet()
Description copied from class:AbstractMultiset
Creates a new instance of this multiset's element set, which will be returned byAbstractMultiset.elementSet()
.- Overrides:
createElementSet
in classAbstractMultiset<E>
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elementIterator
java.util.Iterator<E> elementIterator()
- Specified by:
elementIterator
in classAbstractMultiset<E>
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createEntrySet
@Deprecated public java.util.Set<Multiset.Entry<E>> createEntrySet()
Deprecated.Internal method, useAbstractMultiset.entrySet()
.- Overrides:
createEntrySet
in classAbstractMultiset<E>
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distinctElements
int distinctElements()
- Specified by:
distinctElements
in classAbstractMultiset<E>
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isEmpty
public boolean isEmpty()
- Specified by:
isEmpty
in interfacejava.util.Collection<E>
- Overrides:
isEmpty
in classAbstractMultiset<E>
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entryIterator
java.util.Iterator<Multiset.Entry<E>> entryIterator()
- Specified by:
entryIterator
in classAbstractMultiset<E>
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iterator
public java.util.Iterator<E> iterator()
Description copied from interface:Multiset
Elements that occur multiple times in the multiset will appear multiple times in this iterator, though not necessarily sequentially.
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clear
public void clear()
- Specified by:
clear
in interfacejava.util.Collection<E>
- Specified by:
clear
in classAbstractMultiset<E>
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writeObject
private void writeObject(java.io.ObjectOutputStream stream) throws java.io.IOException
- Throws:
java.io.IOException
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readObject
private void readObject(java.io.ObjectInputStream stream) throws java.io.IOException, java.lang.ClassNotFoundException
- Throws:
java.io.IOException
java.lang.ClassNotFoundException
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