AtomicReferenceArray

AtomicReferenceArray | API reference | Android Developers

public class AtomicReferenceArray
extends Object implements Serializable

An array of object references in which elements may be updated atomically. See the VarHandle specification for descriptions of the properties of atomic accesses.

Summary

Public constructors
`AtomicReferenceArray(E[] array)` Creates a new AtomicReferenceArray with the same length as, and all elements copied from, the given array.
`AtomicReferenceArray(int length)` Creates a new AtomicReferenceArray of the given length, with all elements initially null.

Public methods
`final E`	`accumulateAndGet(int i, E x, BinaryOperator<E> accumulatorFunction)` Atomically updates (with memory effects as specified by `VarHandle.compareAndSet`) the element at index `i` with the results of applying the given function to the current and given values, returning the updated value.
`final E`	`compareAndExchange(int i, E expectedValue, E newValue)` Atomically sets the element at index `i` to `newValue` if the element's current value, referred to as the witness value, `== expectedValue`, with memory effects as specified by `VarHandle.compareAndExchange`.
`final E`	`compareAndExchangeAcquire(int i, E expectedValue, E newValue)` Atomically sets the element at index `i` to `newValue` if the element's current value, referred to as the witness value, `== expectedValue`, with memory effects as specified by `VarHandle.compareAndExchangeAcquire`.
`final E`	`compareAndExchangeRelease(int i, E expectedValue, E newValue)` Atomically sets the element at index `i` to `newValue` if the element's current value, referred to as the witness value, `== expectedValue`, with memory effects as specified by `VarHandle.compareAndExchangeRelease`.
`final boolean`	`compareAndSet(int i, E expectedValue, E newValue)` Atomically sets the element at index `i` to `newValue` if the element's current value `== expectedValue`, with memory effects as specified by `VarHandle.compareAndSet`.
`final E`	`get(int i)` Returns the current value of the element at index `i`, with memory effects as specified by `VarHandle.getVolatile`.
`final E`	`getAcquire(int i)` Returns the current value of the element at index `i`, with memory effects as specified by `VarHandle.getAcquire`.
`final E`	`getAndAccumulate(int i, E x, BinaryOperator<E> accumulatorFunction)` Atomically updates (with memory effects as specified by `VarHandle.compareAndSet`) the element at index `i` with the results of applying the given function to the current and given values, returning the previous value.
`final E`	`getAndSet(int i, E newValue)` Atomically sets the element at index `i` to `newValue` and returns the old value, with memory effects as specified by `VarHandle.getAndSet`.
`final E`	`getAndUpdate(int i, UnaryOperator<E> updateFunction)` Atomically updates (with memory effects as specified by `VarHandle.compareAndSet`) the element at index `i` with the results of applying the given function, returning the previous value.
`final E`	`getOpaque(int i)` Returns the current value of the element at index `i`, with memory effects as specified by `VarHandle.getOpaque`.
`final E`	`getPlain(int i)` Returns the current value of the element at index `i`, with memory semantics of reading as if the variable was declared non-`volatile`.
`final void`	`lazySet(int i, E newValue)` Sets the element at index `i` to `newValue`, with memory effects as specified by `VarHandle.setRelease`.
`final int`	`length()` Returns the length of the array.
`final void`	`set(int i, E newValue)` Sets the element at index `i` to `newValue`, with memory effects as specified by `VarHandle.setVolatile`.
`final void`	`setOpaque(int i, E newValue)` Sets the element at index `i` to `newValue`, with memory effects as specified by `VarHandle.setOpaque`.
`final void`	`setPlain(int i, E newValue)` Sets the element at index `i` to `newValue`, with memory semantics of setting as if the variable was declared non-`volatile` and non-`final`.
`final void`	`setRelease(int i, E newValue)` Sets the element at index `i` to `newValue`, with memory effects as specified by `VarHandle.setRelease`.
`String`	`toString()`
`final E`	`updateAndGet(int i, UnaryOperator<E> updateFunction)` Atomically updates (with memory effects as specified by `VarHandle.compareAndSet`) the element at index `i` with the results of applying the given function, returning the updated value.
`final boolean`	`weakCompareAndSet(int i, E expectedValue, E newValue)` This method was deprecated in API level 33. This method has plain memory effects but the method name implies volatile memory effects (see methods such as `compareAndExchange(int, E, E)` and `compareAndSet(int, E, E)`). To avoid confusion over plain or volatile memory effects it is recommended that the method `weakCompareAndSetPlain(int, E, E)` be used instead.
`final boolean`	`weakCompareAndSetAcquire(int i, E expectedValue, E newValue)` Possibly atomically sets the element at index `i` to `newValue` if the element's current value `== expectedValue`, with memory effects as specified by `VarHandle.weakCompareAndSetAcquire`.
`final boolean`	`weakCompareAndSetPlain(int i, E expectedValue, E newValue)` Possibly atomically sets the element at index `i` to `newValue` if the element's current value `== expectedValue`, with memory effects as specified by `VarHandle.weakCompareAndSetPlain`.
`final boolean`	`weakCompareAndSetRelease(int i, E expectedValue, E newValue)` Possibly atomically sets the element at index `i` to `newValue` if the element's current value `== expectedValue`, with memory effects as specified by `VarHandle.weakCompareAndSetRelease`.
`final boolean`	`weakCompareAndSetVolatile(int i, E expectedValue, E newValue)` Possibly atomically sets the element at index `i` to `newValue` if the element's current value `== expectedValue`, with memory effects as specified by `VarHandle.weakCompareAndSet`.

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.

Public constructors

public AtomicReferenceArray (E[] array)

Creates a new AtomicReferenceArray with the same length as, and all elements copied from, the given array.

Parameters
`array`	`E`: the array to copy elements from

Throws
`NullPointerException`	if array is null

AtomicReferenceArray

public AtomicReferenceArray (int length)

Creates a new AtomicReferenceArray of the given length, with all elements initially null.

Parameters
`length`	`int`: the length of the array

Public methods

accumulateAndGet

public final E accumulateAndGet (int i, 
                E x, 
                BinaryOperator<E> accumulatorFunction)

Atomically updates (with memory effects as specified by VarHandle.compareAndSet) the element at index i 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 of the element at index i as its first argument, and the given update as the second argument.

Parameters
`i`	`int`: the index
`x`	`E`: the update value
`accumulatorFunction`	`BinaryOperator`: a side-effect-free function of two arguments

Returns
`E`	the updated value

compareAndExchange

public final E compareAndExchange (int i, 
                E expectedValue, 
                E newValue)

Atomically sets the element at index i to newValue if the element's current value, referred to as the witness value, == expectedValue, with memory effects as specified by VarHandle.compareAndExchange.

Parameters
`i`	`int`: the index
`expectedValue`	`E`: the expected value
`newValue`	`E`: the new value

Returns
`E`	the witness value, which will be the same as the expected value if successful

compareAndExchangeAcquire

public final E compareAndExchangeAcquire (int i, 
                E expectedValue, 
                E newValue)

Parameters
`i`	`int`: the index
`expectedValue`	`E`: the expected value
`newValue`	`E`: the new value

Returns
`E`	the witness value, which will be the same as the expected value if successful

compareAndExchangeRelease

public final E compareAndExchangeRelease (int i, 
                E expectedValue, 
                E newValue)

Parameters
`i`	`int`: the index
`expectedValue`	`E`: the expected value
`newValue`	`E`: the new value

Returns
`E`	the witness value, which will be the same as the expected value if successful

compareAndSet

public final boolean compareAndSet (int i, 
                E expectedValue, 
                E newValue)

Atomically sets the element at index i to newValue if the element's current value == expectedValue, with memory effects as specified by VarHandle.compareAndSet.

Parameters
`i`	`int`: the index
`expectedValue`	`E`: the expected value
`newValue`	`E`: the new value

Returns
`boolean`	`true` if successful. False return indicates that the actual value was not equal to the expected value.

get

public final E get (int i)

Returns the current value of the element at index i, with memory effects as specified by VarHandle.getVolatile.

Parameters
`i`	`int`: the index

Returns
`E`	the current value

getAcquire

public final E getAcquire (int i)

Returns the current value of the element at index i, with memory effects as specified by VarHandle.getAcquire.

Parameters
`i`	`int`: the index

Returns
`E`	the value

getAndAccumulate

public final E getAndAccumulate (int i, 
                E x, 
                BinaryOperator<E> accumulatorFunction)

Atomically updates (with memory effects as specified by VarHandle.compareAndSet) the element at index i 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 of the element at index i as its first argument, and the given update as the second argument.

Parameters
`i`	`int`: the index
`x`	`E`: the update value
`accumulatorFunction`	`BinaryOperator`: a side-effect-free function of two arguments

Returns
`E`	the previous value

getAndSet

public final E getAndSet (int i, 
                E newValue)

Atomically sets the element at index i to newValue and returns the old value, with memory effects as specified by VarHandle.getAndSet.

Parameters
`i`	`int`: the index
`newValue`	`E`: the new value

Returns
`E`	the previous value

getAndUpdate

public final E getAndUpdate (int i, 
                UnaryOperator<E> updateFunction)

Atomically updates (with memory effects as specified by VarHandle.compareAndSet) the element at index i 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
`i`	`int`: the index
`updateFunction`	`UnaryOperator`: a side-effect-free function

Returns
`E`	the previous value

getOpaque

public final E getOpaque (int i)

Returns the current value of the element at index i, with memory effects as specified by VarHandle.getOpaque.

Parameters
`i`	`int`: the index

Returns
`E`	the value

getPlain

public final E getPlain (int i)

Returns the current value of the element at index i, with memory semantics of reading as if the variable was declared non-volatile.

Parameters
`i`	`int`: the index

Returns
`E`	the value

lazySet

public final void lazySet (int i, 
                E newValue)

Sets the element at index i to newValue, with memory effects as specified by VarHandle.setRelease.

Parameters
`i`	`int`: the index
`newValue`	`E`: the new value

length

public final int length ()

Returns the length of the array.

Returns
`int`	the length of the array

set

public final void set (int i, 
                E newValue)

Sets the element at index i to newValue, with memory effects as specified by VarHandle.setVolatile.

Parameters
`i`	`int`: the index
`newValue`	`E`: the new value

setOpaque

public final void setOpaque (int i, 
                E newValue)

Sets the element at index i to newValue, with memory effects as specified by VarHandle.setOpaque.

Parameters
`i`	`int`: the index
`newValue`	`E`: the new value

setPlain

public final void setPlain (int i, 
                E newValue)

Sets the element at index i to newValue, with memory semantics of setting as if the variable was declared non-volatile and non-final.

Parameters
`i`	`int`: the index
`newValue`	`E`: the new value

setRelease

public final void setRelease (int i, 
                E newValue)

Sets the element at index i to newValue, with memory effects as specified by VarHandle.setRelease.

Parameters
`i`	`int`: the index
`newValue`	`E`: the new value

toString

public String toString ()

Returns
`String`	the String representation of the current values of array

updateAndGet

public final E updateAndGet (int i, 
                UnaryOperator<E> updateFunction)

Atomically updates (with memory effects as specified by VarHandle.compareAndSet) the element at index i 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
`i`	`int`: the index
`updateFunction`	`UnaryOperator`: a side-effect-free function

Returns
`E`	the updated value

weakCompareAndSet

public final boolean weakCompareAndSet (int i, 
                E expectedValue, 
                E newValue)

This method was deprecated in API level 33.
This method has plain memory effects but the method name implies volatile memory effects (see methods such as compareAndExchange(int, E, E) and compareAndSet(int, E, E)). To avoid confusion over plain or volatile memory effects it is recommended that the method weakCompareAndSetPlain(int, E, E) be used instead.

Possibly atomically sets the element at index i to newValue if the element's current value == expectedValue, with memory effects as specified by VarHandle.weakCompareAndSetPlain.

Parameters
`i`	`int`: the index
`expectedValue`	`E`: the expected value
`newValue`	`E`: the new value

Returns
`boolean`	`true` if successful

weakCompareAndSetAcquire

public final boolean weakCompareAndSetAcquire (int i, 
                E expectedValue, 
                E newValue)

Possibly atomically sets the element at index i to newValue if the element's current value == expectedValue, with memory effects as specified by VarHandle.weakCompareAndSetAcquire.

Parameters
`i`	`int`: the index
`expectedValue`	`E`: the expected value
`newValue`	`E`: the new value

Returns
`boolean`	`true` if successful

weakCompareAndSetPlain

public final boolean weakCompareAndSetPlain (int i, 
                E expectedValue, 
                E newValue)

Possibly atomically sets the element at index i to newValue if the element's current value == expectedValue, with memory effects as specified by VarHandle.weakCompareAndSetPlain.

Parameters
`i`	`int`: the index
`expectedValue`	`E`: the expected value
`newValue`	`E`: the new value

Returns
`boolean`	`true` if successful

weakCompareAndSetRelease

public final boolean weakCompareAndSetRelease (int i, 
                E expectedValue, 
                E newValue)

Possibly atomically sets the element at index i to newValue if the element's current value == expectedValue, with memory effects as specified by VarHandle.weakCompareAndSetRelease.

Parameters
`i`	`int`: the index
`expectedValue`	`E`: the expected value
`newValue`	`E`: the new value

Returns
`boolean`	`true` if successful

weakCompareAndSetVolatile

public final boolean weakCompareAndSetVolatile (int i, 
                E expectedValue, 
                E newValue)

Possibly atomically sets the element at index i to newValue if the element's current value == expectedValue, with memory effects as specified by VarHandle.weakCompareAndSet.

Parameters
`i`	`int`: the index
`expectedValue`	`E`: the expected value
`newValue`	`E`: the new value

Returns
`boolean`	`true` if successful