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
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:
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Constructor SummaryConstructorsConstructorDescriptionCreates a new AtomicReference with null initial value.AtomicReference(V initialValue) Creates a new AtomicReference with the given initial value.
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Method SummaryModifier and TypeMethodDescriptionfinal VaccumulateAndGet(V x, BinaryOperator<V> accumulatorFunction) Atomically updates (with memory effects as specified byVarHandle.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.final VcompareAndExchange(V expectedValue, V newValue) Atomically sets the value tonewValueif the current value, referred to as the witness value,== expectedValue, with memory effects as specified byVarHandle.compareAndExchange(java.lang.Object...).final VcompareAndExchangeAcquire(V expectedValue, V newValue) Atomically sets the value tonewValueif the current value, referred to as the witness value,== expectedValue, with memory effects as specified byVarHandle.compareAndExchangeAcquire(java.lang.Object...).final VcompareAndExchangeRelease(V expectedValue, V newValue) Atomically sets the value tonewValueif the current value, referred to as the witness value,== expectedValue, with memory effects as specified byVarHandle.compareAndExchangeRelease(java.lang.Object...).final booleancompareAndSet(V expectedValue, V newValue) Atomically sets the value tonewValueif the current value== expectedValue, with memory effects as specified byVarHandle.compareAndSet(java.lang.Object...).final Vget()Returns the current value, with memory effects as specified byVarHandle.getVolatile(java.lang.Object...).final VReturns the current value, with memory effects as specified byVarHandle.getAcquire(java.lang.Object...).final VgetAndAccumulate(V x, BinaryOperator<V> accumulatorFunction) Atomically updates (with memory effects as specified byVarHandle.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.final VAtomically sets the value tonewValueand returns the old value, with memory effects as specified byVarHandle.getAndSet(java.lang.Object...).final VgetAndUpdate(UnaryOperator<V> updateFunction) Atomically updates (with memory effects as specified byVarHandle.compareAndSet(java.lang.Object...)) the current value with the results of applying the given function, returning the previous value.final VReturns the current value, with memory effects as specified byVarHandle.getOpaque(java.lang.Object...).final VgetPlain()Returns the current value, with memory semantics of reading as if the variable was declared non-volatile.final voidSets the value tonewValue, with memory effects as specified byVarHandle.setRelease(java.lang.Object...).final voidSets the value tonewValue, with memory effects as specified byVarHandle.setVolatile(java.lang.Object...).final voidSets the value tonewValue, with memory effects as specified byVarHandle.setOpaque(java.lang.Object...).final voidSets the value tonewValue, with memory semantics of setting as if the variable was declared non-volatileand non-final.final voidsetRelease(V newValue) Sets the value tonewValue, with memory effects as specified byVarHandle.setRelease(java.lang.Object...).toString()Returns the String representation of the current value.final VupdateAndGet(UnaryOperator<V> updateFunction) Atomically updates (with memory effects as specified byVarHandle.compareAndSet(java.lang.Object...)) the current value with the results of applying the given function, returning the updated value.final booleanweakCompareAndSet(V expectedValue, V newValue) Deprecated.final booleanweakCompareAndSetAcquire(V expectedValue, V newValue) Possibly atomically sets the value tonewValueif the current value== expectedValue, with memory effects as specified byVarHandle.weakCompareAndSetAcquire(java.lang.Object...).final booleanweakCompareAndSetPlain(V expectedValue, V newValue) Possibly atomically sets the value tonewValueif the current value== expectedValue, with memory effects as specified byVarHandle.weakCompareAndSetPlain(java.lang.Object...).final booleanweakCompareAndSetRelease(V expectedValue, V newValue) Possibly atomically sets the value tonewValueif the current value== expectedValue, with memory effects as specified byVarHandle.weakCompareAndSetRelease(java.lang.Object...).final booleanweakCompareAndSetVolatile(V expectedValue, V newValue) Possibly atomically sets the value tonewValueif the current value== expectedValue, with memory effects as specified byVarHandle.weakCompareAndSet(java.lang.Object...).
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Constructor Details- 
AtomicReferenceCreates a new AtomicReference with the given initial value.- Parameters:
- initialValue- the initial value
 
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AtomicReferencepublic AtomicReference()Creates a new AtomicReference with null initial value.
 
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Method Details- 
getReturns the current value, with memory effects as specified byVarHandle.getVolatile(java.lang.Object...).- Returns:
- the current value
 
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setSets the value tonewValue, with memory effects as specified byVarHandle.setVolatile(java.lang.Object...).- Parameters:
- newValue- the new value
 
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lazySetSets the value tonewValue, with memory effects as specified byVarHandle.setRelease(java.lang.Object...).- Parameters:
- newValue- the new value
- Since:
- 1.6
 
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compareAndSetAtomically sets the value tonewValueif the current value== expectedValue, with memory effects as specified byVarHandle.compareAndSet(java.lang.Object...).- Parameters:
- expectedValue- the expected value
- newValue- the new value
- Returns:
- trueif successful. False return indicates that the actual value was not equal to the expected value.
 
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weakCompareAndSetDeprecated.This method has plain memory effects but the method name implies volatile memory effects (see methods such ascompareAndExchange(V, V)andcompareAndSet(V, V)). To avoid confusion over plain or volatile memory effects it is recommended that the methodweakCompareAndSetPlain(V, V)be used instead.Possibly atomically sets the value tonewValueif the current value== expectedValue, with memory effects as specified byVarHandle.weakCompareAndSetPlain(java.lang.Object...).- Parameters:
- expectedValue- the expected value
- newValue- the new value
- Returns:
- trueif successful
- See Also:
 
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weakCompareAndSetPlainPossibly atomically sets the value tonewValueif the current value== expectedValue, with memory effects as specified byVarHandle.weakCompareAndSetPlain(java.lang.Object...).- Parameters:
- expectedValue- the expected value
- newValue- the new value
- Returns:
- trueif successful
- Since:
- 9
 
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getAndSetAtomically sets the value tonewValueand returns the old value, with memory effects as specified byVarHandle.getAndSet(java.lang.Object...).- Parameters:
- newValue- the new value
- Returns:
- the previous value
 
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getAndUpdateAtomically updates (with memory effects as specified byVarHandle.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
 
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updateAndGetAtomically updates (with memory effects as specified byVarHandle.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
 
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getAndAccumulateAtomically updates (with memory effects as specified byVarHandle.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
 
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accumulateAndGetAtomically updates (with memory effects as specified byVarHandle.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
 
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toString
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getPlainReturns the current value, with memory semantics of reading as if the variable was declared non-volatile.- Returns:
- the value
- Since:
- 9
 
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setPlainSets the value tonewValue, with memory semantics of setting as if the variable was declared non-volatileand non-final.- Parameters:
- newValue- the new value
- Since:
- 9
 
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getOpaqueReturns the current value, with memory effects as specified byVarHandle.getOpaque(java.lang.Object...).- Returns:
- the value
- Since:
- 9
 
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setOpaqueSets the value tonewValue, with memory effects as specified byVarHandle.setOpaque(java.lang.Object...).- Parameters:
- newValue- the new value
- Since:
- 9
 
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getAcquireReturns the current value, with memory effects as specified byVarHandle.getAcquire(java.lang.Object...).- Returns:
- the value
- Since:
- 9
 
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setReleaseSets the value tonewValue, with memory effects as specified byVarHandle.setRelease(java.lang.Object...).- Parameters:
- newValue- the new value
- Since:
- 9
 
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compareAndExchangeAtomically sets the value tonewValueif the current value, referred to as the witness value,== expectedValue, with memory effects as specified byVarHandle.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
 
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compareAndExchangeAcquireAtomically sets the value tonewValueif the current value, referred to as the witness value,== expectedValue, with memory effects as specified byVarHandle.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
 
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compareAndExchangeReleaseAtomically sets the value tonewValueif the current value, referred to as the witness value,== expectedValue, with memory effects as specified byVarHandle.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
 
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weakCompareAndSetVolatilePossibly atomically sets the value tonewValueif the current value== expectedValue, with memory effects as specified byVarHandle.weakCompareAndSet(java.lang.Object...).- Parameters:
- expectedValue- the expected value
- newValue- the new value
- Returns:
- trueif successful
- Since:
- 9
 
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weakCompareAndSetAcquirePossibly atomically sets the value tonewValueif the current value== expectedValue, with memory effects as specified byVarHandle.weakCompareAndSetAcquire(java.lang.Object...).- Parameters:
- expectedValue- the expected value
- newValue- the new value
- Returns:
- trueif successful
- Since:
- 9
 
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weakCompareAndSetReleasePossibly atomically sets the value tonewValueif the current value== expectedValue, with memory effects as specified byVarHandle.weakCompareAndSetRelease(java.lang.Object...).- Parameters:
- expectedValue- the expected value
- newValue- the new value
- Returns:
- trueif successful
- Since:
- 9
 
 
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compareAndExchange(V, V)andcompareAndSet(V, V)).