AtomicInteger

public class AtomicInteger extends Number
implements Serializable

An int value that may be updated atomically. See the java.util.concurrent.atomic package specification for description of the properties of atomic variables. 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.

Public Constructor Summary

	AtomicInteger(int initialValue) Creates a new AtomicInteger with the given initial value.
	AtomicInteger() Creates a new AtomicInteger with initial value 0.

Public Method Summary

final int	accumulateAndGet(int x, IntBinaryOperator accumulatorFunction) Atomically updates the current value with the results of applying the given function to the current and given values, returning the updated value.
final int	addAndGet(int delta) Atomically adds the given value to the current value.
final boolean	compareAndSet(int expect, int update) Atomically sets the value to the given updated value if the current value == the expected value.
final int	decrementAndGet() Atomically decrements by one the current value.
double	doubleValue() Returns the value of this AtomicInteger as a double after a widening primitive conversion.
float	floatValue() Returns the value of this AtomicInteger as a float after a widening primitive conversion.
final int	get() Gets the current value.
final int	getAndAccumulate(int x, IntBinaryOperator accumulatorFunction) Atomically updates the current value with the results of applying the given function to the current and given values, returning the previous value.
final int	getAndAdd(int delta) Atomically adds the given value to the current value.
final int	getAndDecrement() Atomically decrements by one the current value.
final int	getAndIncrement() Atomically increments by one the current value.
final int	getAndSet(int newValue) Atomically sets to the given value and returns the old value.
final int	getAndUpdate(IntUnaryOperator updateFunction) Atomically updates the current value with the results of applying the given function, returning the previous value.
final int	incrementAndGet() Atomically increments by one the current value.
int	intValue() Returns the value of this AtomicInteger as an int.
final void	lazySet(int newValue) Eventually sets to the given value.
long	longValue() Returns the value of this AtomicInteger as a long after a widening primitive conversion.
final void	set(int newValue) Sets to the given value.
String	toString() Returns the String representation of the current value.
final int	updateAndGet(IntUnaryOperator updateFunction) Atomically updates the current value with the results of applying the given function, returning the updated value.
final boolean	weakCompareAndSet(int expect, int update) Atomically sets the value to the given updated value if the current value == the expected value.

Inherited Method Summary

From class java.lang.Number

byte	byteValue() Returns the value of the specified number as a byte, which may involve rounding or truncation.
abstract double	doubleValue() Returns the value of the specified number as a double, which may involve rounding.
abstract float	floatValue() Returns the value of the specified number as a float, which may involve rounding.
abstract int	intValue() Returns the value of the specified number as an int, which may involve rounding or truncation.
abstract long	longValue() Returns the value of the specified number as a long, which may involve rounding or truncation.
short	shortValue() Returns the value of the specified number as a short, which may involve rounding or truncation.

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

Public Constructors

public AtomicInteger (int initialValue)

Creates a new AtomicInteger with the given initial value.

Parameters

initialValue	the initial value

public AtomicInteger ()

Creates a new AtomicInteger with initial value 0.

Public Methods

public final int accumulateAndGet (int x, IntBinaryOperator accumulatorFunction)

Atomically updates 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

public final int addAndGet (int delta)

Atomically adds the given value to the current value.

Parameters

delta	the value to add

Returns

• the updated value

public final boolean compareAndSet (int expect, int update)

Atomically sets the value to the given updated value if the current value == the expected value.

Parameters

expect	the expected value
update	the new value

Returns

• true if successful. False return indicates that the actual value was not equal to the expected value.

public final int decrementAndGet ()

Atomically decrements by one the current value.

Returns

• the updated value

public double doubleValue ()

Returns the value of this AtomicInteger as a double after a widening primitive conversion.

Returns

• the numeric value represented by this object after conversion to type double.

public float floatValue ()

Returns the value of this AtomicInteger as a float after a widening primitive conversion.

Returns

• the numeric value represented by this object after conversion to type float.

public final int get ()

Gets the current value.

Returns

• the current value

public final int getAndAccumulate (int x, IntBinaryOperator accumulatorFunction)

Atomically updates 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

public final int getAndAdd (int delta)

Atomically adds the given value to the current value.

Parameters

delta	the value to add

Returns

• the previous value

public final int getAndDecrement ()

Atomically decrements by one the current value.

Returns

• the previous value

public final int getAndIncrement ()

Atomically increments by one the current value.

Returns

• the previous value

public final int getAndSet (int newValue)

Atomically sets to the given value and returns the old value.

Parameters

newValue	the new value

Returns

• the previous value

public final int getAndUpdate (IntUnaryOperator updateFunction)

Atomically updates 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

public final int incrementAndGet ()

Atomically increments by one the current value.

Returns

• the updated value

public int intValue ()

Returns the value of this AtomicInteger as an int. Equivalent to get().

Returns

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

public final void lazySet (int newValue)

Eventually sets to the given value.

Parameters

newValue	the new value

public long longValue ()

Returns the value of this AtomicInteger as a long after a widening primitive conversion.

Returns

• the numeric value represented by this object after conversion to type long.

public final void set (int newValue)

Sets to the given value.

Parameters

newValue	the new value

public String toString ()

Returns the String representation of the current value.

Returns

• the String representation of the current value

public final int updateAndGet (IntUnaryOperator updateFunction)

Atomically updates 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

public final boolean weakCompareAndSet (int expect, int update)

Atomically sets the value to the given updated value if the current value == the expected value.

May fail spuriously and does not provide ordering guarantees, so is only rarely an appropriate alternative to compareAndSet.

Parameters

expect	the expected value
update	the new value

Returns

• true if successful