Class AtomicReferenceArray<E>

java.lang.Object
- java.util.concurrent.atomic.AtomicReferenceArray<E>

Type Parameters:: E - The base class of elements held in this array

All Implemented Interfaces:: Serializable

public class AtomicReferenceArray<E>
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.

Since:: 1.5
See Also:: Serialized Form

Constructor Summary

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

Method Summary

All Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method	Description
`E`	`accumulateAndGet(int i, E x, BinaryOperator<E> accumulatorFunction)`	Atomically updates (with memory effects as specified by `VarHandle.compareAndSet(java.lang.Object...)`) the element at index `i` with the results of applying the given function to the current and given values, returning the updated value.
`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(java.lang.Object...)`.
`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(java.lang.Object...)`.
`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(java.lang.Object...)`.
`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(java.lang.Object...)`.
`E`	`get(int i)`	Returns the current value of the element at index `i`, with memory effects as specified by `VarHandle.getVolatile(java.lang.Object...)`.
`E`	`getAcquire(int i)`	Returns the current value of the element at index `i`, with memory effects as specified by `VarHandle.getAcquire(java.lang.Object...)`.
`E`	`getAndAccumulate(int i, E x, BinaryOperator<E> accumulatorFunction)`	Atomically updates (with memory effects as specified by `VarHandle.compareAndSet(java.lang.Object...)`) the element at index `i` with the results of applying the given function to the current and given values, returning the previous value.
`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(java.lang.Object...)`.
`E`	`getAndUpdate(int i, UnaryOperator<E> updateFunction)`	Atomically updates (with memory effects as specified by `VarHandle.compareAndSet(java.lang.Object...)`) the element at index `i` with the results of applying the given function, returning the previous value.
`E`	`getOpaque(int i)`	Returns the current value of the element at index `i`, with memory effects as specified by `VarHandle.getOpaque(java.lang.Object...)`.
`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`.
`void`	`lazySet(int i, E newValue)`	Sets the element at index `i` to `newValue`, with memory effects as specified by `VarHandle.setRelease(java.lang.Object...)`.
`int`	`length()`	Returns the length of the array.
`void`	`set(int i, E newValue)`	Sets the element at index `i` to `newValue`, with memory effects as specified by `VarHandle.setVolatile(java.lang.Object...)`.
`void`	`setOpaque(int i, E newValue)`	Sets the element at index `i` to `newValue`, with memory effects as specified by `VarHandle.setOpaque(java.lang.Object...)`.
`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`.
`void`	`setRelease(int i, E newValue)`	Sets the element at index `i` to `newValue`, with memory effects as specified by `VarHandle.setRelease(java.lang.Object...)`.
`String`	`toString()`	Returns the String representation of the current values of array.
`E`	`updateAndGet(int i, UnaryOperator<E> updateFunction)`	Atomically updates (with memory effects as specified by `VarHandle.compareAndSet(java.lang.Object...)`) the element at index `i` with the results of applying the given function, returning the updated value.
`boolean`	`weakCompareAndSet(int i, E expectedValue, E newValue)`	Deprecated. 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)`).
`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(java.lang.Object...)`.
`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(java.lang.Object...)`.
`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(java.lang.Object...)`.
`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(java.lang.Object...)`.

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

AtomicReferenceArray

public AtomicReferenceArray(int length)

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

Parameters:: length - the length of the array

AtomicReferenceArray

public AtomicReferenceArray(E[] array)

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

Parameters:: array - the array to copy elements from
Throws:: NullPointerException - if array is null

Method Detail

length

public final int length()

Returns the length of the array.

Returns:: the length of the array

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(java.lang.Object...).

Parameters:: i - the index
Returns:: the current value

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(java.lang.Object...).

Parameters:: i - the index; newValue - the new 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(java.lang.Object...).

Parameters:: i - the index; newValue - the new value
Since:: 1.6

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(java.lang.Object...).

Parameters:: i - the index; newValue - the new value
Returns:: the previous value

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(java.lang.Object...).

Parameters:: i - the index; expectedValue - the expected value; newValue - the new value
Returns:: true if successful. False return indicates that the actual value was not equal to the expected value.

weakCompareAndSet

@Deprecated(since="9")
public final boolean weakCompareAndSet(int i,
                                       E expectedValue,
                                       E newValue)

Deprecated.

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(java.lang.Object...).

Parameters:: i - the index; expectedValue - the expected value; newValue - the new value
Returns:: true if successful
See Also:: weakCompareAndSetPlain(int, E, E)

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(java.lang.Object...).

Parameters:: i - the index; expectedValue - the expected value; newValue - the new value
Returns:: true if successful
Since:: 9

getAndUpdate

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

Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)) 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 - the index; updateFunction - a side-effect-free function
Returns:: the previous value
Since:: 1.8

updateAndGet

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

Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)) 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 - the index; updateFunction - a side-effect-free function
Returns:: the updated value
Since:: 1.8

getAndAccumulate

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

Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)) 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 - the index; x - the update value; accumulatorFunction - a side-effect-free function of two arguments
Returns:: the previous value
Since:: 1.8

accumulateAndGet

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

Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)) 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 - the index; x - the update value; accumulatorFunction - a side-effect-free function of two arguments
Returns:: the updated value
Since:: 1.8

toString

public String toString()

Returns the String representation of the current values of array.

Overrides:: toString in class Object
Returns:: the String representation of the current values of array

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 - the index
Returns:: the value
Since:: 9

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 - the index; newValue - the new value
Since:: 9

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(java.lang.Object...).

Parameters:: i - the index
Returns:: the value
Since:: 9

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(java.lang.Object...).

Parameters:: i - the index; newValue - the new value
Since:: 9

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(java.lang.Object...).

Parameters:: i - the index
Returns:: the value
Since:: 9

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(java.lang.Object...).

Parameters:: i - the index; newValue - the new value
Since:: 9

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(java.lang.Object...).

Parameters:: i - the index; expectedValue - the expected value; newValue - the new value
Returns:: the witness value, which will be the same as the expected value if successful
Since:: 9

compareAndExchangeAcquire

public 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(java.lang.Object...).

Parameters:: i - the index; expectedValue - the expected value; newValue - the new value
Returns:: the witness value, which will be the same as the expected value if successful
Since:: 9

compareAndExchangeRelease

public 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(java.lang.Object...).

Parameters:: i - the index; expectedValue - the expected value; newValue - the new value
Returns:: the witness value, which will be the same as the expected value if successful
Since:: 9

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(java.lang.Object...).

Parameters:: i - the index; expectedValue - the expected value; newValue - the new value
Returns:: true if successful
Since:: 9

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(java.lang.Object...).

Parameters:: i - the index; expectedValue - the expected value; newValue - the new value
Returns:: true if successful
Since:: 9

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(java.lang.Object...).

Parameters:: i - the index; expectedValue - the expected value; newValue - the new value
Returns:: true if successful
Since:: 9