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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:

Constructor Summary

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

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)

Parameters:: updateFunction - a side-effect-free function
Returns:: the previous value
Since:: 1.8

updateAndGet

public final long updateAndGet(LongUnaryOperator updateFunction)

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)

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)

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

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