Added in API level 1

Summary: Protected Ctors | Methods | Inherited Methods

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.

Object arguments for parameters of type T that are not instances of the class passed to newUpdater(Class, String) will result in a ClassCastException being thrown.

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 (with memory effects as specified by VarHandle.compareAndSet(Object)) 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) Returns 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 (with memory effects as specified by VarHandle.compareAndSet(Object)) 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 (with memory effects as specified by VarHandle.compareAndSet(Object)) 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 (with memory effects as specified by VarHandle.compareAndSet(Object)) 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 Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Protected constructors

AtomicLongFieldUpdater

Added in API level 1

protected AtomicLongFieldUpdater ()

Protected do-nothing constructor for use by subclasses.

Public methods

accumulateAndGet

Added in API level 24

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

Atomically updates (with memory effects as specified by VarHandle.compareAndSet(Object)) 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

public 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

public 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. 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

decrementAndGet

Added in API level 1

public 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

public abstract long get (T obj)

Returns 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

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

Atomically updates (with memory effects as specified by VarHandle.compareAndSet(Object)) 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

public 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

public 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

public 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

public 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

public final long getAndUpdate (T obj, 
                LongUnaryOperator updateFunction)

Atomically updates (with memory effects as specified by VarHandle.compareAndSet(Object)) 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

public 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

public abstract 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

public static 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

public abstract 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

public final long updateAndGet (T obj, 
                LongUnaryOperator updateFunction)

Atomically updates (with memory effects as specified by VarHandle.compareAndSet(Object)) 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

public 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. 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.

This operation 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