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

Class AtomicReferenceArray<E>

java.lang.Object
java.util.concurrent.atomic.AtomicReferenceArray<E>
Type Parameters:
E - The base class of elements held in this array
All Implemented Interfaces:
Serializable
public class AtomicReferenceArray<E> extends Object implements Serializable
An array of object references in which elements may be updated atomically. See the VarHandle specification for descriptions of the properties of atomic accesses.
Since:
1.5
See Also:
Serialized Form

  • Constructor Details

    • AtomicReferenceArray

      public AtomicReferenceArray​(int length)
      Creates a new AtomicReferenceArray of the given length, with all elements initially null.
      Parameters:
      length - the length of the array

    • AtomicReferenceArray

      public AtomicReferenceArray​(E[] array)
      Creates a new AtomicReferenceArray with the same length as, and all elements copied from, the given array.
      Parameters:
      array - the array to copy elements from
      Throws:
      NullPointerException - if array is null

  • Method Details

    • length

      public final int length()
      Returns the length of the array.
      Returns:
      the length of the array

    • get

      public final E get​(int i)
      Returns the current value of the element at index i, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...).
      Parameters:
      i - the index
      Returns:
      the current value

    • set

      public final void set​(int i, E newValue)
      Sets the element at index i to newValue, with memory effects as specified by VarHandle.setVolatile(java.lang.Object...).
      Parameters:
      i - the index
      newValue - the new value

    • lazySet

      public final void lazySet​(int i, E newValue)
      Sets the element at index i to newValue, with memory effects as specified by VarHandle.setRelease(java.lang.Object...).
      Parameters:
      i - the index
      newValue - the new value
      Since:
      1.6

    • getAndSet

      public final E getAndSet​(int i, E newValue)
      Atomically sets the element at index i to newValue and returns the old value, with memory effects as specified by VarHandle.getAndSet(java.lang.Object...).
      Parameters:
      i - the index
      newValue - the new value
      Returns:
      the previous value

    • compareAndSet

      public final boolean compareAndSet​(int i, E expectedValue, E newValue)
      Atomically sets the element at index i to newValue if the element's current value == expectedValue, with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...).
      Parameters:
      i - the index
      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​(int i, E expectedValue, E newValue)
      Deprecated.
      This method has plain memory effects but the method name implies volatile memory effects (see methods such as compareAndExchange(int, E, E) and compareAndSet(int, E, E)). To avoid confusion over plain or volatile memory effects it is recommended that the method weakCompareAndSetPlain(int, E, E) be used instead.
      Possibly atomically sets the element at index i to newValue if the element's current value == expectedValue, with memory effects as specified by VarHandle.weakCompareAndSetPlain(java.lang.Object...).
      Parameters:
      i - the index
      expectedValue - the expected value
      newValue - the new value
      Returns:
      true if successful
      See Also:
      weakCompareAndSetPlain(int, E, E)

    • weakCompareAndSetPlain

      public final boolean weakCompareAndSetPlain​(int i, E expectedValue, E newValue)
      Possibly atomically sets the element at index i to newValue if the element's current value == expectedValue, with memory effects as specified by VarHandle.weakCompareAndSetPlain(java.lang.Object...).
      Parameters:
      i - the index
      expectedValue - the expected value
      newValue - the new value
      Returns:
      true if successful
      Since:
      9

    • getAndUpdate

      public final E getAndUpdate​(int i, UnaryOperator<E> updateFunction)
      Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)) the element at index i 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:
      i - the index
      updateFunction - a side-effect-free function
      Returns:
      the previous value
      Since:
      1.8

    • updateAndGet

      public final E updateAndGet​(int i, UnaryOperator<E> updateFunction)
      Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)) the element at index i 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:
      i - the index
      updateFunction - a side-effect-free function
      Returns:
      the updated value
      Since:
      1.8

    • getAndAccumulate

      public final E getAndAccumulate​(int i, E x, BinaryOperator<E> accumulatorFunction)
      Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)) the element at index i 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 of the element at index i as its first argument, and the given update as the second argument.
      Parameters:
      i - the index
      x - the update value
      accumulatorFunction - a side-effect-free function of two arguments
      Returns:
      the previous value
      Since:
      1.8

    • accumulateAndGet

      public final E accumulateAndGet​(int i, E x, BinaryOperator<E> accumulatorFunction)
      Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)) the element at index i 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 of the element at index i as its first argument, and the given update as the second argument.
      Parameters:
      i - the index
      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 values of array.
      Overrides:
      toString in class Object
      Returns:
      the String representation of the current values of array

    • getPlain

      public final E getPlain​(int i)
      Returns the current value of the element at index i, with memory semantics of reading as if the variable was declared non-volatile.
      Parameters:
      i - the index
      Returns:
      the value
      Since:
      9

    • setPlain

      public final void setPlain​(int i, E newValue)
      Sets the element at index i to newValue, with memory semantics of setting as if the variable was declared non-volatile and non-final.
      Parameters:
      i - the index
      newValue - the new value
      Since:
      9

    • getOpaque

      public final E getOpaque​(int i)
      Returns the current value of the element at index i, with memory effects as specified by VarHandle.getOpaque(java.lang.Object...).
      Parameters:
      i - the index
      Returns:
      the value
      Since:
      9

    • setOpaque

      public final void setOpaque​(int i, E newValue)
      Sets the element at index i to newValue, with memory effects as specified by VarHandle.setOpaque(java.lang.Object...).
      Parameters:
      i - the index
      newValue - the new value
      Since:
      9

    • getAcquire

      public final E getAcquire​(int i)
      Returns the current value of the element at index i, with memory effects as specified by VarHandle.getAcquire(java.lang.Object...).
      Parameters:
      i - the index
      Returns:
      the value
      Since:
      9

    • setRelease

      public final void setRelease​(int i, E newValue)
      Sets the element at index i to newValue, with memory effects as specified by VarHandle.setRelease(java.lang.Object...).
      Parameters:
      i - the index
      newValue - the new value
      Since:
      9

    • compareAndExchange

      public final E compareAndExchange​(int i, E expectedValue, E newValue)
      Atomically sets the element at index i to newValue if the element's current value, referred to as the witness value, == expectedValue, with memory effects as specified by VarHandle.compareAndExchange(java.lang.Object...).
      Parameters:
      i - the index
      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 E compareAndExchangeAcquire​(int i, E expectedValue, E newValue)
      Atomically sets the element at index i to newValue if the element's current value, referred to as the witness value, == expectedValue, with memory effects as specified by VarHandle.compareAndExchangeAcquire(java.lang.Object...).
      Parameters:
      i - the index
      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 E compareAndExchangeRelease​(int i, E expectedValue, E newValue)
      Atomically sets the element at index i to newValue if the element's current value, referred to as the witness value, == expectedValue, with memory effects as specified by VarHandle.compareAndExchangeRelease(java.lang.Object...).
      Parameters:
      i - the index
      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​(int i, E expectedValue, E newValue)
      Possibly atomically sets the element at index i to newValue if the element's current value == expectedValue, with memory effects as specified by VarHandle.weakCompareAndSet(java.lang.Object...).
      Parameters:
      i - the index
      expectedValue - the expected value
      newValue - the new value
      Returns:
      true if successful
      Since:
      9

    • weakCompareAndSetAcquire

      public final boolean weakCompareAndSetAcquire​(int i, E expectedValue, E newValue)
      Possibly atomically sets the element at index i to newValue if the element's current value == expectedValue, with memory effects as specified by VarHandle.weakCompareAndSetAcquire(java.lang.Object...).
      Parameters:
      i - the index
      expectedValue - the expected value
      newValue - the new value
      Returns:
      true if successful
      Since:
      9

    • weakCompareAndSetRelease

      public final boolean weakCompareAndSetRelease​(int i, E expectedValue, E newValue)
      Possibly atomically sets the element at index i to newValue if the element's current value == expectedValue, with memory effects as specified by VarHandle.weakCompareAndSetRelease(java.lang.Object...).
      Parameters:
      i - the index
      expectedValue - the expected value
      newValue - the new value
      Returns:
      true if successful
      Since:
      9