|
||||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Objectjava.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 |
---|
Nested classes/interfaces inherited from interface com.google.common.collect.Multiset |
---|
Multiset.Entry<E> |
Method Summary | ||
---|---|---|
boolean |
add(E element)
Ensures that this collection contains the specified element. |
|
int |
add(E element,
int occurrences)
Adds a number of occurrences of the specified element to this multiset. |
|
boolean |
addAll(Collection<? extends E> elementsToAdd)
Adds all of the elements in the specified collection to this multiset. |
|
void |
clear()
Removes all of the elements from this multiset. |
|
boolean |
contains(Object element)
Returns true if this collection contains the specified element. |
|
boolean |
containsAll(Collection<?> elements)
Returns true if this multiset contains all of the elements in the
specified collection. |
|
int |
count(Object element)
Returns the number of occurrences of element in this multiset. |
|
static
|
create()
Creates a new empty ConcurrentHashMultiset using the default
initial capacity, load factor, and concurrency settings. |
|
static
|
create(Iterable<? extends E> elements)
Creates a new ConcurrentHashMultiset containing the specified
elements, using the default initial capacity, load factor, and concurrency
settings. |
|
protected Set<E> |
createElementSet()
Creates a new instance of this multiset's element set, which will be returned by elementSet() . |
|
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(Object object)
Compares the specified object with this multiset for equality. |
|
int |
hashCode()
Returns the hash code for this multiset. |
|
boolean |
isEmpty()
|
|
Iterator<E> |
iterator()
|
|
boolean |
remove(Object element)
Removes a single instance of the specified element from this collection, if it is present. |
|
int |
remove(Object element,
int occurrences)
Removes a number of occurrences of the specified element from this multiset. |
|
boolean |
removeAll(Collection<?> elementsToRemove)
Removes all of this multiset's elements that are also contained in the specified collection. |
|
boolean |
removeExactly(Object element,
int occurrences)
Removes exactly the specified number of occurrences of element , or
makes no change if this is not possible. |
|
boolean |
retainAll(Collection<?> elementsToRetain)
Retains only the elements in this multiset that are contained in the specified collection. |
|
int |
setCount(E element,
int count)
Adds or removes occurrences of element such that the count(java.lang.Object)
of the element becomes count . |
|
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 . |
|
int |
size()
|
|
Object[] |
toArray()
|
|
|
toArray(T[] array)
|
|
String |
toString()
|
Methods inherited from class java.lang.Object |
---|
clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Method Detail |
---|
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()
This implementation iterates across Multiset.entrySet()
and
sums the counts of the entries.
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
negativeprotected Set<E> createElementSet()
elementSet()
.
public 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)
true
if this collection contains the specified element.
This implementation checks whether elementSet
contains the
element.
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()
This implementation usually invokes methods of the
Multiset.entrySet()
iterator. However, the iterator's
remove
method sometimes calls the multiset's remove
.
iterator
in interface Iterable<E>
iterator
in interface Collection<E>
iterator
in class AbstractCollection<E>
public boolean add(@Nullable E element)
This implementation calls add(Object, int)
with one occurrence.
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
alwayspublic boolean remove(Object element)
This implementation calls remove(Object, int)
with 1
occurrence.
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)
true
if this multiset contains all of the elements in the
specified collection.
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.
This implementation checks whether elementSet
contains the
elements.
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)
If the collection being added is a multiset, this implementation
iterates over that multiset's entry set to add the appropriate number of
occurrences of each of its elements to this multiset. Otherwise, it calls
AbstractCollection.addAll(java.util.Collection extends E>)
.
addAll
in interface Collection<E>
addAll
in class AbstractCollection<E>
public boolean removeAll(Collection<?> elementsToRemove)
This implementation calls removeAll()
on its
elementSet()
with the given collection or, if
elementsToRemove
is a multiset, the elements in its element set. In
some cases, this approach has better performance than
AbstractCollection.removeAll(java.util.Collection>)
.
removeAll
in interface Multiset<E>
removeAll
in interface Collection<E>
removeAll
in class AbstractCollection<E>
public boolean retainAll(Collection<?> elementsToRetain)
This implementation iterates over entrySet()
, checking each
entry's element to see if it's contained in the provided collection.
If it's not found, the remove
method of the entry set's
iterator is invoked. In some cases, this approach has better performance
than AbstractCollection.removeAll(java.util.Collection>)
.
retainAll
in interface Multiset<E>
retainAll
in interface Collection<E>
retainAll
in class AbstractCollection<E>
public void clear()
This implementation calls clear
on Multiset.entrySet()
.
clear
in interface Collection<E>
clear
in class AbstractCollection<E>
public Set<E> elementSet()
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()
.
The returned set's methods are implemented by calling
Multiset.entrySet()
methods.
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.
TODO: caveats about equivalence-relation.
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>
|
||||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |