com.google.common.util.concurrent
Class AtomicDoubleArray

java.lang.Object
  extended by com.google.common.util.concurrent.AtomicDoubleArray
All Implemented Interfaces:
Serializable

@Beta
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;
 }

Since:
11.0
Author:
Doug Lea, Martin Buchholz
See Also:
Serialized Form

Constructor Summary
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
 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


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