Class AtomicReference<V>
- java.lang.Object
-
- java.util.concurrent.atomic.AtomicReference<V>
- Type Parameters:
-
V
- The type of object referred to by this reference
- All Implemented Interfaces:
Serializable
public class AtomicReference<V> extends Object implements Serializable
An object reference that 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
Constructor | Description |
---|---|
AtomicReference() | Creates a new AtomicReference with null initial value. |
AtomicReference(V initialValue) | Creates a new AtomicReference with the given initial value. |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
V | accumulateAndGet(V x,
BinaryOperator<V> accumulatorFunction) | Atomically updates (with memory effects as specified by |
V | compareAndExchange(V expectedValue,
V newValue) | Atomically sets the value to |
V | compareAndExchangeAcquire(V expectedValue,
V newValue) | Atomically sets the value to |
V | compareAndExchangeRelease(V expectedValue,
V newValue) | Atomically sets the value to |
boolean | compareAndSet(V expectedValue,
V newValue) | Atomically sets the value to |
V | get() | Returns the current value, with memory effects as specified by |
V | getAcquire() | Returns the current value, with memory effects as specified by |
V | getAndAccumulate(V x,
BinaryOperator<V> accumulatorFunction) | Atomically updates (with memory effects as specified by |
V | getAndSet(V newValue) | Atomically sets the value to |
V | getAndUpdate(UnaryOperator<V> updateFunction) | Atomically updates (with memory effects as specified by |
V | getOpaque() | Returns the current value, with memory effects as specified by |
V | getPlain() | Returns the current value, with memory semantics of reading as if the variable was declared non- |
void | lazySet(V newValue) | Sets the value to |
void | set(V newValue) | Sets the value to |
void | setOpaque(V newValue) | Sets the value to |
void | setPlain(V newValue) | Sets the value to |
void | setRelease(V newValue) | Sets the value to |
String | toString() | Returns the String representation of the current value. |
V | updateAndGet(UnaryOperator<V> updateFunction) | Atomically updates (with memory effects as specified by |
boolean | weakCompareAndSet(V expectedValue,
V newValue) | Deprecated. This method has plain memory effects but the method name implies volatile memory effects (see methods such as compareAndExchange(V, V) and compareAndSet(V, V) ). |
boolean | weakCompareAndSetAcquire(V expectedValue,
V newValue) | Possibly atomically sets the value to |
boolean | weakCompareAndSetPlain(V expectedValue,
V newValue) | Possibly atomically sets the value to |
boolean | weakCompareAndSetRelease(V expectedValue,
V newValue) | Possibly atomically sets the value to |
boolean | weakCompareAndSetVolatile(V expectedValue,
V newValue) | Possibly atomically sets the value to |
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Constructor Detail
AtomicReference
public AtomicReference(V initialValue)
Creates a new AtomicReference with the given initial value.
- Parameters:
-
initialValue
- the initial value
AtomicReference
public AtomicReference()
Creates a new AtomicReference with null initial value.
Method Detail
get
public final V get()
Returns the current value, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...)
.
- Returns:
- the current value
set
public final void set(V newValue)
Sets the value to newValue
, with memory effects as specified by VarHandle.setVolatile(java.lang.Object...)
.
- Parameters:
-
newValue
- the new value
lazySet
public final void lazySet(V newValue)
Sets the value to newValue
, with memory effects as specified by VarHandle.setRelease(java.lang.Object...)
.
- Parameters:
-
newValue
- the new value - Since:
- 1.6
compareAndSet
public final boolean compareAndSet(V expectedValue, V newValue)
Atomically sets the value to newValue
if the current value == expectedValue
, with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)
.
- Parameters:
-
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(V expectedValue, V newValue)
compareAndExchange(V, V)
and compareAndSet(V, V)
). To avoid confusion over plain or volatile memory effects it is recommended that the method weakCompareAndSetPlain(V, V)
be used instead.Possibly atomically sets the value to newValue
if the current value == expectedValue
, with memory effects as specified by VarHandle.weakCompareAndSetPlain(java.lang.Object...)
.
- Parameters:
-
expectedValue
- the expected value -
newValue
- the new value - Returns:
-
true
if successful - See Also:
weakCompareAndSetPlain(V, V)
weakCompareAndSetPlain
public final boolean weakCompareAndSetPlain(V expectedValue, V newValue)
Possibly atomically sets the value to newValue
if the current value == expectedValue
, with memory effects as specified by VarHandle.weakCompareAndSetPlain(java.lang.Object...)
.
- Parameters:
-
expectedValue
- the expected value -
newValue
- the new value - Returns:
-
true
if successful - Since:
- 9
getAndSet
public final V getAndSet(V newValue)
Atomically sets the value to newValue
and returns the old value, with memory effects as specified by VarHandle.getAndSet(java.lang.Object...)
.
- Parameters:
-
newValue
- the new value - Returns:
- the previous value
getAndUpdate
public final V getAndUpdate(UnaryOperator<V> updateFunction)
Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)
) the current value 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:
-
updateFunction
- a side-effect-free function - Returns:
- the previous value
- Since:
- 1.8
updateAndGet
public final V updateAndGet(UnaryOperator<V> updateFunction)
Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)
) the current value 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:
-
updateFunction
- a side-effect-free function - Returns:
- the updated value
- Since:
- 1.8
getAndAccumulate
public final V getAndAccumulate(V x, BinaryOperator<V> accumulatorFunction)
Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)
) the current value 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:
-
x
- the update value -
accumulatorFunction
- a side-effect-free function of two arguments - Returns:
- the previous value
- Since:
- 1.8
accumulateAndGet
public final V accumulateAndGet(V x, BinaryOperator<V> accumulatorFunction)
Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)
) the current value 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:
-
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 value.
getPlain
public final V getPlain()
Returns the current value, with memory semantics of reading as if the variable was declared non-volatile
.
- Returns:
- the value
- Since:
- 9
setPlain
public final void setPlain(V newValue)
Sets the value to newValue
, with memory semantics of setting as if the variable was declared non-volatile
and non-final
.
- Parameters:
-
newValue
- the new value - Since:
- 9
getOpaque
public final V getOpaque()
Returns the current value, with memory effects as specified by VarHandle.getOpaque(java.lang.Object...)
.
- Returns:
- the value
- Since:
- 9
setOpaque
public final void setOpaque(V newValue)
Sets the value to newValue
, with memory effects as specified by VarHandle.setOpaque(java.lang.Object...)
.
- Parameters:
-
newValue
- the new value - Since:
- 9
getAcquire
public final V getAcquire()
Returns the current value, with memory effects as specified by VarHandle.getAcquire(java.lang.Object...)
.
- Returns:
- the value
- Since:
- 9
setRelease
public final void setRelease(V newValue)
Sets the value to newValue
, with memory effects as specified by VarHandle.setRelease(java.lang.Object...)
.
- Parameters:
-
newValue
- the new value - Since:
- 9
compareAndExchange
public final V compareAndExchange(V expectedValue, V newValue)
Atomically sets the value to newValue
if the current value, referred to as the witness value, == expectedValue
, with memory effects as specified by VarHandle.compareAndExchange(java.lang.Object...)
.
- Parameters:
-
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 V compareAndExchangeAcquire(V expectedValue, V newValue)
Atomically sets the value to newValue
if the current value, referred to as the witness value, == expectedValue
, with memory effects as specified by VarHandle.compareAndExchangeAcquire(java.lang.Object...)
.
- Parameters:
-
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 V compareAndExchangeRelease(V expectedValue, V newValue)
Atomically sets the value to newValue
if the current value, referred to as the witness value, == expectedValue
, with memory effects as specified by VarHandle.compareAndExchangeRelease(java.lang.Object...)
.
- Parameters:
-
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(V expectedValue, V newValue)
Possibly atomically sets the value to newValue
if the current value == expectedValue
, with memory effects as specified by VarHandle.weakCompareAndSet(java.lang.Object...)
.
- Parameters:
-
expectedValue
- the expected value -
newValue
- the new value - Returns:
-
true
if successful - Since:
- 9
weakCompareAndSetAcquire
public final boolean weakCompareAndSetAcquire(V expectedValue, V newValue)
Possibly atomically sets the value to newValue
if the current value == expectedValue
, with memory effects as specified by VarHandle.weakCompareAndSetAcquire(java.lang.Object...)
.
- Parameters:
-
expectedValue
- the expected value -
newValue
- the new value - Returns:
-
true
if successful - Since:
- 9
weakCompareAndSetRelease
public final boolean weakCompareAndSetRelease(V expectedValue, V newValue)
Possibly atomically sets the value to newValue
if the current value == expectedValue
, with memory effects as specified by VarHandle.weakCompareAndSetRelease(java.lang.Object...)
.
- Parameters:
-
expectedValue
- the expected value -
newValue
- the new value - Returns:
-
true
if successful - Since:
- 9