Module java.base

Class AtomicInteger

  • All Implemented Interfaces:
    java.io.Serializable


    public class AtomicInteger
    extends java.lang.Number
    implements java.io.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 Summary

      Constructors 
      Constructor Description
      AtomicInteger​()
      Creates a new AtomicInteger with initial value 0.
      AtomicInteger​(int initialValue)
      Creates a new AtomicInteger with the given initial value.
    • Method Summary

      All Methods Instance Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      int accumulateAndGet​(int x, java.util.function.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.
      int addAndGet​(int delta)
      Atomically adds the given value to the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).
      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...).
      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...).
      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...).
      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...).
      int decrementAndGet​()
      Atomically decrements the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).
      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...).
      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...).
      int get​()
      Returns the current value, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...).
      int getAcquire​()
      Returns the current value, with memory effects as specified by VarHandle.getAcquire(java.lang.Object...).
      int getAndAccumulate​(int x, java.util.function.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.
      int getAndAdd​(int delta)
      Atomically adds the given value to the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).
      int getAndDecrement​()
      Atomically decrements the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).
      int getAndIncrement​()
      Atomically increments the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).
      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...).
      int getAndUpdate​(java.util.function.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.
      int getOpaque​()
      Returns the current value, with memory effects as specified by VarHandle.getOpaque(java.lang.Object...).
      int getPlain​()
      Returns the current value, with memory semantics of reading as if the variable was declared non-volatile.
      int incrementAndGet​()
      Atomically increments the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).
      int intValue​()
      Returns the current value of this AtomicInteger as an int, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...).
      void lazySet​(int newValue)
      Sets the value to newValue, with memory effects as specified by VarHandle.setRelease(java.lang.Object...).
      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...).
      void set​(int newValue)
      Sets the value to newValue, with memory effects as specified by VarHandle.setVolatile(java.lang.Object...).
      void setOpaque​(int newValue)
      Sets the value to newValue, with memory effects as specified by VarHandle.setOpaque(java.lang.Object...).
      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.
      void setRelease​(int newValue)
      Sets the value to newValue, with memory effects as specified by VarHandle.setRelease(java.lang.Object...).
      java.lang.String toString​()
      Returns the String representation of the current value.
      int updateAndGet​(java.util.function.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.
      boolean weakCompareAndSet​(int expectedValue, int newValue)
      Deprecated. 
      This method has plain memory effects but the method name implies volatile memory effects (see methods such as compareAndExchange(int, int) and compareAndSet(int, int)). To avoid confusion over plain or volatile memory effects it is recommended that the method weakCompareAndSetPlain(int, int) be used instead.
      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...).
      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...).
      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...).
      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...).
      • Methods inherited from class java.lang.Number

        byteValue, shortValue
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • 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

      • get

        public final int 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​(int 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​(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.
      • weakCompareAndSet

        @Deprecated(since="9")
        public final boolean weakCompareAndSet​(int expectedValue,
                                               int newValue)
        Deprecated. This method has plain memory effects but the method name implies volatile memory effects (see methods such as compareAndExchange(int, int) and compareAndSet(int, int)). To avoid confusion over plain or volatile memory effects it is recommended that the method weakCompareAndSetPlain(int, int) 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(int, int)
      • 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​(java.util.function.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​(java.util.function.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,
                                          java.util.function.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,
                                          java.util.function.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 java.lang.String toString​()
        Returns the String representation of the current value.
        Overrides:
        toString in class java.lang.Object
        Returns:
        the String representation of the current value
      • intValue

        public int intValue​()
        Returns the current value of this AtomicInteger as an int, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...). Equivalent to get().
        Specified by:
        intValue in class java.lang.Number
      • 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 java.lang.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 java.lang.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 java.lang.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
      • getOpaque

        public final int 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​(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
      • getAcquire

        public final int 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​(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