Module java.base

Class AtomicInteger

  • All Implemented Interfaces:
    Serializable


    public class AtomicInteger
    extends Number
    implements Serializable
    An int value that may be updated atomically. See the VarHandle specification for descriptions of the properties of atomic accesses. An AtomicInteger is used in applications such as atomically incremented counters, and cannot be used as a replacement for an Integer. However, this class does extend Number to allow uniform access by tools and utilities that deal with numerically-based classes.
    Since:
    1.5
    Author:
    Doug Lea
    See Also:
    Serialized Form
    • Constructor Detail

      • AtomicInteger

        public AtomicInteger​(int initialValue)
        Creates a new AtomicInteger with the given initial value.
        Parameters:
        initialValue - the initial value
      • AtomicInteger

        public AtomicInteger​()
        Creates a new AtomicInteger with initial value 0.
    • Method Detail

      • lazySet

        public final void lazySet​(int 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
      • getAndSet

        public final int getAndSet​(int 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
      • compareAndSet

        public final boolean compareAndSet​(int expectedValue,
                                           int 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​(int expectedValue,
                                                    int 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
      • getAndIncrement

        public final int getAndIncrement​()
        Atomically increments the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).

        Equivalent to getAndAdd(1).

        Returns:
        the previous value
      • getAndDecrement

        public final int getAndDecrement​()
        Atomically decrements the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).

        Equivalent to getAndAdd(-1).

        Returns:
        the previous value
      • getAndAdd

        public final int getAndAdd​(int delta)
        Atomically adds the given value to the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).
        Parameters:
        delta - the value to add
        Returns:
        the previous value
      • incrementAndGet

        public final int incrementAndGet​()
        Atomically increments the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).

        Equivalent to addAndGet(1).

        Returns:
        the updated value
      • decrementAndGet

        public final int decrementAndGet​()
        Atomically decrements the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).

        Equivalent to addAndGet(-1).

        Returns:
        the updated value
      • addAndGet

        public final int addAndGet​(int delta)
        Atomically adds the given value to the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).
        Parameters:
        delta - the value to add
        Returns:
        the updated value
      • getAndUpdate

        public final int getAndUpdate​(IntUnaryOperator 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 int updateAndGet​(IntUnaryOperator 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 int getAndAccumulate​(int x,
                                          IntBinaryOperator 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 int accumulateAndGet​(int x,
                                          IntBinaryOperator 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
      • longValue

        public long longValue​()
        Returns the current value of this AtomicInteger as a long after a widening primitive conversion, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...).
        Specified by:
        longValue in class Number
        See The Java™ Language Specification:
        5.1.2 Widening Primitive Conversions
      • floatValue

        public float floatValue​()
        Returns the current value of this AtomicInteger as a float after a widening primitive conversion, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...).
        Specified by:
        floatValue in class Number
        See The Java™ Language Specification:
        5.1.2 Widening Primitive Conversions
      • doubleValue

        public double doubleValue​()
        Returns the current value of this AtomicInteger as a double after a widening primitive conversion, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...).
        Specified by:
        doubleValue in class Number
        See The Java™ Language Specification:
        5.1.2 Widening Primitive Conversions
      • getPlain

        public final int 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​(int 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​(int 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​(int 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 int compareAndExchange​(int expectedValue,
                                            int 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 int compareAndExchangeAcquire​(int expectedValue,
                                                   int 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 int compareAndExchangeRelease​(int expectedValue,
                                                   int 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​(int expectedValue,
                                                       int 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​(int expectedValue,
                                                      int 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​(int expectedValue,
                                                      int 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