Module java.base

Package java.util.concurrent.atomic

Class AtomicLong

java.lang.Object

java.lang.Number

java.util.concurrent.atomic.AtomicLong

All Implemented Interfaces:

Serializable

public class AtomicLong
extends Number
implements Serializable

A long value that may be updated atomically. See the VarHandle specification for descriptions of the properties of atomic accesses. An AtomicLong is used in applications such as atomically incremented sequence numbers, and cannot be used as a replacement for a Long. 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
AtomicLong()	Creates a new AtomicLong with initial value 0.
AtomicLong(long initialValue)	Creates a new AtomicLong with the given initial value.

Method Summary

Modifier and Type	Method	Description
final long	accumulateAndGet(long x, LongBinaryOperator 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.
final long	addAndGet(long delta)	Atomically adds the given value to the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).
final long	compareAndExchange(long expectedValue, long 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...).
final long	compareAndExchangeAcquire(long expectedValue, long 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...).
final long	compareAndExchangeRelease(long expectedValue, long 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...).
final boolean	compareAndSet(long expectedValue, long newValue)	Atomically sets the value to newValue if the current value == expectedValue, with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...).
final long	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 AtomicLong 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 AtomicLong as a float after a widening primitive conversion, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...).
final long	get()	Returns the current value, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...).
final long	getAcquire()	Returns the current value, with memory effects as specified by VarHandle.getAcquire(java.lang.Object...).
final long	getAndAccumulate(long x, LongBinaryOperator 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.
final long	getAndAdd(long delta)	Atomically adds the given value to the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).
final long	getAndDecrement()	Atomically decrements the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).
final long	getAndIncrement()	Atomically increments the current value, with memory effects as specified by VarHandle.getAndAdd(java.lang.Object...).
final long	getAndSet(long newValue)	Atomically sets the value to newValue and returns the old value, with memory effects as specified by VarHandle.getAndSet(java.lang.Object...).
final long	getAndUpdate(LongUnaryOperator 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.
final long	getOpaque()	Returns the current value, with memory effects as specified by VarHandle.getOpaque(java.lang.Object...).
final long	getPlain()	Returns the current value, with memory semantics of reading as if the variable was declared non-volatile.
final long	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 AtomicLong as an int after a narrowing primitive conversion, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...).
final void	lazySet(long 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 AtomicLong as a long, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...).
final void	set(long newValue)	Sets the value to newValue, with memory effects as specified by VarHandle.setVolatile(java.lang.Object...).
final void	setOpaque(long newValue)	Sets the value to newValue, with memory effects as specified by VarHandle.setOpaque(java.lang.Object...).
final void	setPlain(long newValue)	Sets the value to newValue, with memory semantics of setting as if the variable was declared non-volatile and non-final.
final void	setRelease(long 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.
final long	updateAndGet(LongUnaryOperator 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.
final boolean	weakCompareAndSet(long expectedValue, long newValue)	Deprecated. This method has plain memory effects but the method name implies volatile memory effects (see methods such as compareAndExchange(long, long) and compareAndSet(long, long)).
final boolean	weakCompareAndSetAcquire(long expectedValue, long newValue)	Possibly atomically sets the value to newValue if the current value == expectedValue, with memory effects as specified by VarHandle.weakCompareAndSetAcquire(java.lang.Object...).
final boolean	weakCompareAndSetPlain(long expectedValue, long newValue)	Possibly atomically sets the value to newValue if the current value == expectedValue, with memory effects as specified by VarHandle.weakCompareAndSetPlain(java.lang.Object...).
final boolean	weakCompareAndSetRelease(long expectedValue, long newValue)	Possibly atomically sets the value to newValue if the current value == expectedValue, with memory effects as specified by VarHandle.weakCompareAndSetRelease(java.lang.Object...).
final boolean	weakCompareAndSetVolatile(long expectedValue, long 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 Details

AtomicLong

public AtomicLong(long initialValue)

Creates a new AtomicLong with the given initial value.

Parameters:

initialValue - the initial value

AtomicLong

public AtomicLong()

Creates a new AtomicLong with initial value 0.

Method Details

get

public final long 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(long 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(long 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 long getAndSet(long 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(long expectedValue,
 long 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(long expectedValue,
 long newValue)

Deprecated.

This method has plain memory effects but the method name implies volatile memory effects (see methods such as compareAndExchange(long, long) and compareAndSet(long, long)). To avoid confusion over plain or volatile memory effects it is recommended that the method weakCompareAndSetPlain(long, long) 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(long, long)

weakCompareAndSetPlain

public final boolean weakCompareAndSetPlain(long expectedValue,
 long 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 long 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 long 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 long getAndAdd(long 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 long 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 long 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 long addAndGet(long 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 long getAndUpdate(LongUnaryOperator 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 long updateAndGet(LongUnaryOperator 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 long getAndAccumulate(long x,
 LongBinaryOperator 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 long accumulateAndGet(long x,
 LongBinaryOperator 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 AtomicLong as an int after a narrowing primitive conversion, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...).

Specified by:

intValue in class Number

Returns:

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

See Java Language Specification:

5.1.3 Narrowing Primitive Conversion

longValue

public long longValue()

Returns the current value of this AtomicLong as a long, with memory effects as specified by VarHandle.getVolatile(java.lang.Object...). Equivalent to get().

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 AtomicLong 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 AtomicLong 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 long 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(long 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 long 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(long 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 long 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(long 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 long compareAndExchange(long expectedValue,
 long 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 long compareAndExchangeAcquire(long expectedValue,
 long 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 long compareAndExchangeRelease(long expectedValue,
 long 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(long expectedValue,
 long 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(long expectedValue,
 long 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(long expectedValue,
 long 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