- java.lang.Object
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- java.util.concurrent.atomic.AtomicReference<V>
 
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- 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 theVarHandlespecification for descriptions of the properties of atomic accesses.- Since:
- 1.5
- See Also:
- Serialized Form
 
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Constructor SummaryConstructors Constructor Description AtomicReference()Creates a new AtomicReference with null initial value.AtomicReference(V initialValue)Creates a new AtomicReference with the given initial value.
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Method SummaryAll Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method Description 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.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...).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...).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...).booleancompareAndSet(V expectedValue, V newValue)Atomically sets the value tonewValueif the current value== expectedValue, with memory effects as specified byVarHandle.compareAndSet(java.lang.Object...).Vget()Returns the current value, with memory effects as specified byVarHandle.getVolatile(java.lang.Object...).VgetAcquire()Returns the current value, with memory effects as specified byVarHandle.getAcquire(java.lang.Object...).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.VgetAndSet(V newValue)Atomically sets the value tonewValueand returns the old value, with memory effects as specified byVarHandle.getAndSet(java.lang.Object...).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.VgetOpaque()Returns the current value, with memory effects as specified byVarHandle.getOpaque(java.lang.Object...).VgetPlain()Returns the current value, with memory semantics of reading as if the variable was declared non-volatile.voidlazySet(V newValue)Sets the value tonewValue, with memory effects as specified byVarHandle.setRelease(java.lang.Object...).voidset(V newValue)Sets the value tonewValue, with memory effects as specified byVarHandle.setVolatile(java.lang.Object...).voidsetOpaque(V newValue)Sets the value tonewValue, with memory effects as specified byVarHandle.setOpaque(java.lang.Object...).voidsetPlain(V newValue)Sets the value tonewValue, with memory semantics of setting as if the variable was declared non-volatileand non-final.voidsetRelease(V newValue)Sets the value tonewValue, with memory effects as specified byVarHandle.setRelease(java.lang.Object...).StringtoString()Returns the String representation of the current value.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.booleanweakCompareAndSet(V expectedValue, V newValue)Deprecated.This method has plain memory effects but the method name implies volatile memory effects (see methods such ascompareAndExchange(V, V)andcompareAndSet(V, V)).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...).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...).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...).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 Detail- 
AtomicReferencepublic AtomicReference(V initialValue) Creates 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 Detail- 
getpublic final V get() Returns the current value, with memory effects as specified byVarHandle.getVolatile(java.lang.Object...).- Returns:
- the current value
 
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setpublic final void set(V newValue) Sets the value tonewValue, with memory effects as specified byVarHandle.setVolatile(java.lang.Object...).- Parameters:
- newValue- the new value
 
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lazySetpublic final void lazySet(V newValue) Sets 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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compareAndSetpublic final boolean compareAndSet(V expectedValue, V newValue) Atomically 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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weakCompareAndSet@Deprecated(since="9") public final boolean weakCompareAndSet(V expectedValue, V newValue) Deprecated.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:
- weakCompareAndSetPlain(V, V)
 
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weakCompareAndSetPlainpublic final boolean weakCompareAndSetPlain(V expectedValue, V newValue) 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
- Since:
- 9
 
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getAndSetpublic final V getAndSet(V newValue) Atomically 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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getAndUpdatepublic final V getAndUpdate(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. 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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updateAndGetpublic final V updateAndGet(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. 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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getAndAccumulatepublic final V getAndAccumulate(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. 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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accumulateAndGetpublic final V accumulateAndGet(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. 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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toStringpublic String toString() Returns the String representation of the current value.
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getPlainpublic 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
 
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setPlainpublic final void setPlain(V newValue) Sets 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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getOpaquepublic final V getOpaque() Returns the current value, with memory effects as specified byVarHandle.getOpaque(java.lang.Object...).- Returns:
- the value
- Since:
- 9
 
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setOpaquepublic final void setOpaque(V newValue) Sets the value tonewValue, with memory effects as specified byVarHandle.setOpaque(java.lang.Object...).- Parameters:
- newValue- the new value
- Since:
- 9
 
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getAcquirepublic final V getAcquire() Returns the current value, with memory effects as specified byVarHandle.getAcquire(java.lang.Object...).- Returns:
- the value
- Since:
- 9
 
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setReleasepublic final void setRelease(V newValue) Sets the value tonewValue, with memory effects as specified byVarHandle.setRelease(java.lang.Object...).- Parameters:
- newValue- the new value
- Since:
- 9
 
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compareAndExchangepublic final V compareAndExchange(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...).- 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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compareAndExchangeAcquirepublic final V compareAndExchangeAcquire(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...).- 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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compareAndExchangeReleasepublic final V compareAndExchangeRelease(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...).- 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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weakCompareAndSetVolatilepublic final boolean weakCompareAndSetVolatile(V expectedValue, V newValue) Possibly 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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weakCompareAndSetAcquirepublic final boolean weakCompareAndSetAcquire(V expectedValue, V newValue) Possibly 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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weakCompareAndSetReleasepublic final boolean weakCompareAndSetRelease(V expectedValue, V newValue) Possibly 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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