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
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, 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, 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​(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...).
String toString()

Returns the String representation of the current value.
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.
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)).
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 declared in class java.lang.Number

byteValue, shortValue

Methods declared in 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​(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.

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.

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.

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