jsr166e.extra

Class AtomicDoubleArray

java.lang.Object

jsr166e.extra.AtomicDoubleArray

All Implemented Interfaces:

Serializable

public class AtomicDoubleArray
extends Object
implements Serializable

A double array in which elements may be updated atomically. See the java.util.concurrent.atomic package specification for description of the properties of atomic variables.

This class compares primitive double values in methods such as compareAndSet(int, 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;
 }

Author:

Doug Lea, Martin Buchholz

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
AtomicDoubleArray(double[] array) Creates a new AtomicDoubleArray with the same length as, and all elements copied from, the given array.
AtomicDoubleArray(int length) Creates a new AtomicDoubleArray of the given length, with all elements initially zero.

Method Summary

Methods

Modifier and Type	Method and Description
double	addAndGet(int i, double delta) Atomically adds the given value to the element at index i.
boolean	compareAndSet(int i, double expect, double update) Atomically sets the element at position i to the given updated value if the current value is bitwise equal to the expected value.
double	get(int i) Gets the current value at position i.
double	getAndAdd(int i, double delta) Atomically adds the given value to the element at index i.
double	getAndSet(int i, double newValue) Atomically sets the element at position i to the given value and returns the old value.
void	lazySet(int i, double newValue) Eventually sets the element at position i to the given value.
int	length() Returns the length of the array.
void	set(int i, double newValue) Sets the element at position i to the given value.
String	toString() Returns the String representation of the current values of array.
boolean	weakCompareAndSet(int i, double expect, double update) Atomically sets the element at position i to the given updated value if the current value is bitwise equal to the expected value.

Methods inherited from class java.lang.Object

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

Constructor Detail

AtomicDoubleArray

public AtomicDoubleArray(int length)

Creates a new AtomicDoubleArray of the given length, with all elements initially zero.

Parameters:

length - the length of the array

AtomicDoubleArray

public AtomicDoubleArray(double[] array)

Creates a new AtomicDoubleArray with the same length as, and all elements copied from, the given array.

Parameters:

array - the array to copy elements from

Throws:

NullPointerException - if array is null

Method Detail

length

public final int length()

Returns the length of the array.

Returns:

the length of the array

get

public final double get(int i)

Gets the current value at position i.

Parameters:

i - the index

Returns:

the current value

set

public final void set(int i,
       double newValue)

Sets the element at position i to the given value.

Parameters:

i - the index

newValue - the new value

lazySet

public final void lazySet(int i,
           double newValue)

Eventually sets the element at position i to the given value.

Parameters:

i - the index

newValue - the new value

getAndSet

public final double getAndSet(int i,
               double newValue)

Atomically sets the element at position i to the given value and returns the old value.

Parameters:

i - the index

newValue - the new value

Returns:

the previous value

compareAndSet

public final boolean compareAndSet(int i,
                    double expect,
                    double update)

Atomically sets the element at position i to the given updated value if the current value is bitwise equal to the expected value.

Parameters:

i - the index

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.

weakCompareAndSet

public final boolean weakCompareAndSet(int i,
                        double expect,
                        double update)

Atomically sets the element at position i 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:

i - the index

expect - the expected value

update - the new value

Returns:

true if successful

getAndAdd

public final double getAndAdd(int i,
               double delta)

Atomically adds the given value to the element at index i.

Parameters:

i - the index

delta - the value to add

Returns:

the previous value

addAndGet

public double addAndGet(int i,
               double delta)

Atomically adds the given value to the element at index i.

Parameters:

i - the index

delta - the value to add

Returns:

the updated value

toString

public String toString()

Returns the String representation of the current values of array.

Overrides:

toString in class Object

Returns:

the String representation of the current values of array