Class AtomicInteger

java.lang.Object
java.lang.Number
java.util.concurrent.atomic.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
See Also:

  • Constructor Details

    • 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 Details

    • 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

      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

    • 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 Number
      Returns:
      the numeric value represented by this object after conversion to type int.

    • 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
      Returns:
      the numeric value represented by this object after conversion to type long.
      See Java Language Specification:
      5.1.2 Widening Primitive Conversion

    • 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
      Returns:
      the numeric value represented by this object after conversion to type float.
      See Java Language Specification:
      5.1.2 Widening Primitive Conversion

    • 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
      Returns:
      the numeric value represented by this object after conversion to type double.
      See Java Language Specification:
      5.1.2 Widening Primitive Conversion

    • 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