Class AtomicLongMap<K>
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- com.google.common.util.concurrent.AtomicLongMap<K>
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- All Implemented Interfaces:
@GwtCompatible public final class AtomicLongMap<K> extends implements
A map containinglong
values that can be atomically updated. While writes to a traditionalMap
rely onput(K, V)
, the typical mechanism for writing to this map isaddAndGet(K, long)
, which adds along
to the value currently associated withK
. If a key has not yet been associated with a value, its implicit value is zero.Most methods in this class treat absent values and zero values identically, as individually documented. Exceptions to this are
containsKey(java.lang.Object)
,size()
,isEmpty()
,asMap
, andtoString()
.Instances of this class may be used by multiple threads concurrently. All operations are atomic unless otherwise noted.
Note: If your values are always positive and less than 2^31, you may wish to use a
Multiset
such asConcurrentHashMultiset
instead.Warning: Unlike
Multiset
, entries whose values are zero are not automatically removed from the map. Instead they must be removed manually withremoveAllZeros()
.- Since:
- 11.0
- Author:
- Charles Fry
- See Also:
- Serialized Form
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description long
accumulateAndGet(K key, long x, accumulatorFunction)
Updates the value currently associated withkey
by combining it withx
via the specified accumulator function, returning the new value.long
addAndGet(K key, long delta)
Addsdelta
to the value currently associated withkey
, and returns the new value.<>
asMap()
Returns a live, read-only view of the map backing thisAtomicLongMap
.void
clear()
Removes all of the mappings from this map.boolean
key)
Returns true if this map contains a mapping for the specified key.static <K> AtomicLongMap<K>
create()
Creates anAtomicLongMap
.static <K> AtomicLongMap<K>
<? extends K,? extends > m)
Creates anAtomicLongMap
with the same mappings as the specifiedMap
.long
decrementAndGet(K key)
Decrements by one the value currently associated withkey
, and returns the new value.long
get(K key)
Returns the value associated withkey
, or zero if there is no value associated withkey
.long
getAndAccumulate(K key, long x, accumulatorFunction)
Updates the value currently associated withkey
by combining it withx
via the specified accumulator function, returning the old value.long
getAndAdd(K key, long delta)
Addsdelta
to the value currently associated withkey
, and returns the old value.long
getAndDecrement(K key)
Decrements by one the value currently associated withkey
, and returns the old value.long
getAndIncrement(K key)
Increments by one the value currently associated withkey
, and returns the old value.long
getAndUpdate(K key, updaterFunction)
Updates the value currently associated withkey
with the specified function, and returns the old value.long
incrementAndGet(K key)
Increments by one the value currently associated withkey
, and returns the new value.boolean
isEmpty()
Returnstrue
if this map contains no key-value mappings.long
put(K key, long newValue)
AssociatesnewValue
withkey
in this map, and returns the value previously associated withkey
, or zero if there was no such value.void
<? extends > m)
Copies all of the mappings from the specified map to this map.long
remove(K key)
Removes and returns the value associated withkey
.void
removeAllZeros()
Removes all mappings from this map whose values are zero.boolean
removeIfZero(K key)
Atomically removekey
from the map iff its associated value is 0.int
size()
Returns the number of key-value mappings in this map.long
sum()
Returns the sum of all values in this map.toString()
Returns a string representation of the object.long
updateAndGet(K key, updaterFunction)
Updates the value currently associated withkey
with the specified function, and returns the new value.
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Method Detail
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create
public static <K> AtomicLongMap<K> create()
Creates anAtomicLongMap
.
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create
public static <K> <? extends K,? extends > m)
Creates anAtomicLongMap
with the same mappings as the specifiedMap
.
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get
public long get(K key)
Returns the value associated withkey
, or zero if there is no value associated withkey
.
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incrementAndGet
public long incrementAndGet(K key)
Increments by one the value currently associated withkey
, and returns the new value.
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decrementAndGet
public long decrementAndGet(K key)
Decrements by one the value currently associated withkey
, and returns the new value.
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addAndGet
public long addAndGet(K key, long delta)
Addsdelta
to the value currently associated withkey
, and returns the new value.
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getAndIncrement
public long getAndIncrement(K key)
Increments by one the value currently associated withkey
, and returns the old value.
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getAndDecrement
public long getAndDecrement(K key)
Decrements by one the value currently associated withkey
, and returns the old value.
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getAndAdd
public long getAndAdd(K key, long delta)
Addsdelta
to the value currently associated withkey
, and returns the old value.
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updateAndGet
public long updateAndGet(K key, updaterFunction)
Updates the value currently associated withkey
with the specified function, and returns the new value. If there is not currently a value associated withkey
, the function is applied to0L
.- Since:
- 21.0
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getAndUpdate
public long getAndUpdate(K key, updaterFunction)
Updates the value currently associated withkey
with the specified function, and returns the old value. If there is not currently a value associated withkey
, the function is applied to0L
.- Since:
- 21.0
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accumulateAndGet
public long accumulateAndGet(K key, long x, accumulatorFunction)
Updates the value currently associated withkey
by combining it withx
via the specified accumulator function, returning the new value. The previous value associated withkey
(or zero, if there is none) is passed as the first argument toaccumulatorFunction
, andx
is passed as the second argument.- Since:
- 21.0
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getAndAccumulate
public long getAndAccumulate(K key, long x, accumulatorFunction)
Updates the value currently associated withkey
by combining it withx
via the specified accumulator function, returning the old value. The previous value associated withkey
(or zero, if there is none) is passed as the first argument toaccumulatorFunction
, andx
is passed as the second argument.- Since:
- 21.0
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put
public long put(K key, long newValue)
AssociatesnewValue
withkey
in this map, and returns the value previously associated withkey
, or zero if there was no such value.
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putAll
public void <? extends > m)
Copies all of the mappings from the specified map to this map. The effect of this call is equivalent to that of callingput(k, v)
on this map once for each mapping from keyk
to valuev
in the specified map. The behavior of this operation is undefined if the specified map is modified while the operation is in progress.
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remove
public long remove(K key)
Removes and returns the value associated withkey
. Ifkey
is not in the map, this method has no effect and returns zero.
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removeIfZero
@Beta public boolean removeIfZero(K key)
Atomically removekey
from the map iff its associated value is 0.- Since:
- 20.0
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removeAllZeros
public void removeAllZeros()
Removes all mappings from this map whose values are zero.This method is not atomic: the map may be visible in intermediate states, where some of the zero values have been removed and others have not.
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sum
public long sum()
Returns the sum of all values in this map.This method is not atomic: the sum may or may not include other concurrent operations.
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asMap
public <> asMap()
Returns a live, read-only view of the map backing thisAtomicLongMap
.
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containsKey
public boolean key)
Returns true if this map contains a mapping for the specified key.
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size
public int size()
Returns the number of key-value mappings in this map. If the map contains more thanInteger.MAX_VALUE
elements, returnsInteger.MAX_VALUE
.
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isEmpty
public boolean isEmpty()
Returnstrue
if this map contains no key-value mappings.
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clear
public void clear()
Removes all of the mappings from this map. The map will be empty after this call returns.This method is not atomic: the map may not be empty after returning if there were concurrent writes.
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toString
public toString()
Description copied from class:Returns a string representation of the object. In general, thetoString
method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.The
toString
method for classObject
returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@
', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:getClass().getName() + '@' + Integer.toHexString(hashCode())
- Overrides:
in class
- Returns:
- a string representation of the object.
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