Module java.base
Package java.util.concurrent.atomic

Class 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 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

      • 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.

      • 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

      • 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

      • 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