com.google.common.util.concurrent

Class AtomicDouble

java.lang.Object

java.lang.Number

com.google.common.util.concurrent.AtomicDouble

All Implemented Interfaces:

Serializable

public class AtomicDouble
extends Number
implements Serializable

A double value that may be updated atomically. See the java.util.concurrent.atomic package specification for description of the properties of atomic variables. An AtomicDouble is used in applications such as atomic accumulation, and cannot be used as a replacement for a Double. However, this class does extend Number to allow uniform access by tools and utilities that deal with numerically-based classes.

This class compares primitive double values in methods such as compareAndSet(double, double) by comparing their bitwise representation using Double.doubleToRawLongBits(double), which differs from both the primitive double == operator and from Double.equals(java.lang.Object), as if implemented by:

 static boolean bitEquals(double x, double y) {
   long xBits = Double.doubleToRawLongBits(x);
   long yBits = Double.doubleToRawLongBits(y);
   return xBits == yBits;
 }
 

It is possible to write a more scalable updater, at the cost of giving up strict atomicity. See for example DoubleAdder and DoubleMaxUpdater.

Since:

11.0

Author:

Doug Lea, Martin Buchholz

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
AtomicDouble() Creates a new AtomicDouble with initial value 0.0.
AtomicDouble(double initialValue) Creates a new AtomicDouble with the given initial value.

Method Summary

Modifier and Type	Method and Description
double	addAndGet(double delta) Atomically adds the given value to the current value.
boolean	compareAndSet(double expect, double update) Atomically sets the value to the given updated value if the current value is bitwise equal to the expected value.
double	doubleValue() Returns the value of this AtomicDouble as a double.
float	floatValue() Returns the value of this AtomicDouble as a float after a narrowing primitive conversion.
double	get() Gets the current value.
double	getAndAdd(double delta) Atomically adds the given value to the current value.
double	getAndSet(double newValue) Atomically sets to the given value and returns the old value.
int	intValue() Returns the value of this AtomicDouble as an int after a narrowing primitive conversion.
void	lazySet(double newValue) Eventually sets to the given value.
long	longValue() Returns the value of this AtomicDouble as a long after a narrowing primitive conversion.
void	set(double newValue) Sets to the given value.
String	toString() Returns the String representation of the current value.
boolean	weakCompareAndSet(double expect, double update) Atomically sets the value to the given updated value if the current value is bitwise equal to the expected value.

Methods inherited from class java.lang.Number

byteValue, shortValue

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

AtomicDouble

public AtomicDouble(double initialValue)

Creates a new AtomicDouble with the given initial value.

Parameters:

initialValue - the initial value

AtomicDouble

public AtomicDouble()

Creates a new AtomicDouble with initial value 0.0.

Method Detail

get

public final double get()

Gets the current value.

Returns:

the current value

set

public final void set(double newValue)

Sets to the given value.

Parameters:

newValue - the new value

lazySet

public final void lazySet(double newValue)

Eventually sets to the given value.

Parameters:

newValue - the new value

getAndSet

public final double getAndSet(double newValue)

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

Parameters:

newValue - the new value

Returns:

the previous value

compareAndSet

public final boolean compareAndSet(double expect,
                                   double update)

Atomically sets the value to the given updated value if the current value is bitwise equal to 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 bitwise equal to the expected value.

weakCompareAndSet

public final boolean weakCompareAndSet(double expect,
                                       double update)

Atomically sets the value to the given updated value if the current value is bitwise equal to 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

getAndAdd

public final double getAndAdd(double delta)

Atomically adds the given value to the current value.

Parameters:

delta - the value to add

Returns:

the previous value

addAndGet

public final double addAndGet(double delta)

Atomically adds the given value to the current value.

Parameters:

delta - the value to add

Returns:

the updated value

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 value of this AtomicDouble as an int after a narrowing primitive conversion.

Specified by:

intValue in class Number

longValue

public long longValue()

Returns the value of this AtomicDouble as a long after a narrowing primitive conversion.

Specified by:

longValue in class Number

floatValue

public float floatValue()

Returns the value of this AtomicDouble as a float after a narrowing primitive conversion.

Specified by:

floatValue in class Number

doubleValue

public double doubleValue()

Returns the value of this AtomicDouble as a double.

Specified by:

doubleValue in class Number