Java Module java.base Package java.util.concurrent.atomic Class AtomicReference<V>（JDK11）

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)

  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)). 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.

  Overrides:

  toString in class Object

  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