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Added in API level 1

AtomicLongFieldUpdater

public abstract class AtomicLongFieldUpdater
extends Object

java.lang.Object
   ↳ java.util.concurrent.atomic.AtomicLongFieldUpdater<T>


A reflection-based utility that enables atomic updates to designated volatile long fields of designated classes. This class is designed for use in atomic data structures in which several fields of the same node are independently subject to atomic updates.

Note that the guarantees of the compareAndSet method in this class are weaker than in other atomic classes. Because this class cannot ensure that all uses of the field are appropriate for purposes of atomic access, it can guarantee atomicity only with respect to other invocations of compareAndSet and set on the same updater.

Summary

Protected constructors

AtomicLongFieldUpdater()

Protected do-nothing constructor for use by subclasses.

Public methods

final long accumulateAndGet(T obj, long x, LongBinaryOperator accumulatorFunction)

Atomically updates the field of the given object managed by this updater with the results of applying the given function to the current and given values, returning the updated value.

long addAndGet(T obj, long delta)

Atomically adds the given value to the current value of the field of the given object managed by this updater.

abstract boolean compareAndSet(T obj, long expect, long update)

Atomically sets the field of the given object managed by this updater to the given updated value if the current value == the expected value.

long decrementAndGet(T obj)

Atomically decrements by one the current value of the field of the given object managed by this updater.

abstract long get(T obj)

Gets the current value held in the field of the given object managed by this updater.

final long getAndAccumulate(T obj, long x, LongBinaryOperator accumulatorFunction)

Atomically updates the field of the given object managed by this updater with the results of applying the given function to the current and given values, returning the previous value.

long getAndAdd(T obj, long delta)

Atomically adds the given value to the current value of the field of the given object managed by this updater.

long getAndDecrement(T obj)

Atomically decrements by one the current value of the field of the given object managed by this updater.

long getAndIncrement(T obj)

Atomically increments by one the current value of the field of the given object managed by this updater.

long getAndSet(T obj, long newValue)

Atomically sets the field of the given object managed by this updater to the given value and returns the old value.

final long getAndUpdate(T obj, LongUnaryOperator updateFunction)

Atomically updates the field of the given object managed by this updater with the results of applying the given function, returning the previous value.

long incrementAndGet(T obj)

Atomically increments by one the current value of the field of the given object managed by this updater.

abstract void lazySet(T obj, long newValue)

Eventually sets the field of the given object managed by this updater to the given updated value.

static <U> AtomicLongFieldUpdater<U> newUpdater(Class<U> tclass, String fieldName)

Creates and returns an updater for objects with the given field.

abstract void set(T obj, long newValue)

Sets the field of the given object managed by this updater to the given updated value.

final long updateAndGet(T obj, LongUnaryOperator updateFunction)

Atomically updates the field of the given object managed by this updater with the results of applying the given function, returning the updated value.

abstract boolean weakCompareAndSet(T obj, long expect, long update)

Atomically sets the field of the given object managed by this updater to the given updated value if the current value == the expected value.

Inherited methods

From class java.lang.Object

Protected constructors

AtomicLongFieldUpdater

Added in API level 1
AtomicLongFieldUpdater ()

Protected do-nothing constructor for use by subclasses.

Public methods

accumulateAndGet

Added in API level 24
long accumulateAndGet (T obj, 
                long x, 
                LongBinaryOperator accumulatorFunction)

Atomically updates the field of the given object managed by this updater with the results of applying the given function to the current and given values, returning the updated value. The function should be side-effect-free, since it may be re-applied when attempted updates fail due to contention among threads. The function is applied with the current value as its first argument, and the given update as the second argument.

Parameters
obj T: An object whose field to get and set
x long: the update value
accumulatorFunction LongBinaryOperator: a side-effect-free function of two arguments
Returns
long the updated value

addAndGet

Added in API level 1
long addAndGet (T obj, 
                long delta)

Atomically adds the given value to the current value of the field of the given object managed by this updater.

Parameters
obj T: An object whose field to get and set
delta long: the value to add
Returns
long the updated value

compareAndSet

Added in API level 1
boolean compareAndSet (T obj, 
                long expect, 
                long update)

Atomically sets the field of the given object managed by this updater to the given updated value if the current value == the expected value. This method is guaranteed to be atomic with respect to other calls to compareAndSet and set, but not necessarily with respect to other changes in the field.

Parameters
obj T: An object whose field to conditionally set
expect long: the expected value
update long: the new value
Returns
boolean true if successful
Throws
ClassCastException if obj is not an instance of the class possessing the field established in the constructor

decrementAndGet

Added in API level 1
long decrementAndGet (T obj)

Atomically decrements by one the current value of the field of the given object managed by this updater.

Parameters
obj T: An object whose field to get and set
Returns
long the updated value

get

Added in API level 1
long get (T obj)

Gets the current value held in the field of the given object managed by this updater.

Parameters
obj T: An object whose field to get
Returns
long the current value

getAndAccumulate

Added in API level 24
long getAndAccumulate (T obj, 
                long x, 
                LongBinaryOperator accumulatorFunction)

Atomically updates the field of the given object managed by this updater with the results of applying the given function to the current and given values, returning the previous value. The function should be side-effect-free, since it may be re-applied when attempted updates fail due to contention among threads. The function is applied with the current value as its first argument, and the given update as the second argument.

Parameters
obj T: An object whose field to get and set
x long: the update value
accumulatorFunction LongBinaryOperator: a side-effect-free function of two arguments
Returns
long the previous value

getAndAdd

Added in API level 1
long getAndAdd (T obj, 
                long delta)

Atomically adds the given value to the current value of the field of the given object managed by this updater.

Parameters
obj T: An object whose field to get and set
delta long: the value to add
Returns
long the previous value

getAndDecrement

Added in API level 1
long getAndDecrement (T obj)

Atomically decrements by one the current value of the field of the given object managed by this updater.

Parameters
obj T: An object whose field to get and set
Returns
long the previous value

getAndIncrement

Added in API level 1
long getAndIncrement (T obj)

Atomically increments by one the current value of the field of the given object managed by this updater.

Parameters
obj T: An object whose field to get and set
Returns
long the previous value

getAndSet

Added in API level 1
long getAndSet (T obj, 
                long newValue)

Atomically sets the field of the given object managed by this updater to the given value and returns the old value.

Parameters
obj T: An object whose field to get and set
newValue long: the new value
Returns
long the previous value

getAndUpdate

Added in API level 24
long getAndUpdate (T obj, 
                LongUnaryOperator updateFunction)

Atomically updates the field of the given object managed by this updater with the results of applying the given function, returning the previous value. The function should be side-effect-free, since it may be re-applied when attempted updates fail due to contention among threads.

Parameters
obj T: An object whose field to get and set
updateFunction LongUnaryOperator: a side-effect-free function
Returns
long the previous value

incrementAndGet

Added in API level 1
long incrementAndGet (T obj)

Atomically increments by one the current value of the field of the given object managed by this updater.

Parameters
obj T: An object whose field to get and set
Returns
long the updated value

lazySet

Added in API level 9
void lazySet (T obj, 
                long newValue)

Eventually sets the field of the given object managed by this updater to the given updated value.

Parameters
obj T: An object whose field to set
newValue long: the new value

newUpdater

Added in API level 1
AtomicLongFieldUpdater<U> newUpdater (Class<U> tclass, 
                String fieldName)

Creates and returns an updater for objects with the given field. The Class argument is needed to check that reflective types and generic types match.

Parameters
tclass Class: the class of the objects holding the field
fieldName String: the name of the field to be updated
Returns
AtomicLongFieldUpdater<U> the updater
Throws
IllegalArgumentException if the field is not a volatile long type
RuntimeException with a nested reflection-based exception if the class does not hold field or is the wrong type, or the field is inaccessible to the caller according to Java language access control

set

Added in API level 1
void set (T obj, 
                long newValue)

Sets the field of the given object managed by this updater to the given updated value. This operation is guaranteed to act as a volatile store with respect to subsequent invocations of compareAndSet.

Parameters
obj T: An object whose field to set
newValue long: the new value

updateAndGet

Added in API level 24
long updateAndGet (T obj, 
                LongUnaryOperator updateFunction)

Atomically updates the field of the given object managed by this updater with the results of applying the given function, returning the updated value. The function should be side-effect-free, since it may be re-applied when attempted updates fail due to contention among threads.

Parameters
obj T: An object whose field to get and set
updateFunction LongUnaryOperator: a side-effect-free function
Returns
long the updated value

weakCompareAndSet

Added in API level 1
boolean weakCompareAndSet (T obj, 
                long expect, 
                long update)

Atomically sets the field of the given object managed by this updater to the given updated value if the current value == the expected value. This method is guaranteed to be atomic with respect to other calls to compareAndSet and set, but not necessarily with respect to other changes in the field.

May fail spuriously and does not provide ordering guarantees, so is only rarely an appropriate alternative to compareAndSet.

Parameters
obj T: An object whose field to conditionally set
expect long: the expected value
update long: the new value
Returns
boolean true if successful
Throws
ClassCastException if obj is not an instance of the class possessing the field established in the constructor
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