Serializable
public class DoubleAdder extends Number implements Serializable
double
sum. When updates (method add(double)
) are contended across threads, the set of variables may grow dynamically to reduce contention. Method sum()
(or, equivalently doubleValue()
) returns the current total combined across the variables maintaining the sum. The order of accumulation within or across threads is not guaranteed. Thus, this class may not be applicable if numerical stability is required, especially when combining values of substantially different orders of magnitude. This class is usually preferable to alternatives when multiple threads update a common value that is used for purposes such as summary statistics that are frequently updated but less frequently read.
This class extends Number
, but does not define methods such as equals
, hashCode
and
compareTo
because instances are expected to be mutated, and so are not useful as collection keys.
Constructor | Description |
---|---|
DoubleAdder() |
Creates a new adder with initial sum of zero. |
Modifier and Type | Method | Description |
---|---|---|
void |
add |
Adds the given value. |
double |
doubleValue() |
Equivalent to sum() . |
float |
floatValue() |
Returns the sum() as a float after a narrowing primitive conversion. |
int |
intValue() |
Returns the sum() as an int after a narrowing primitive conversion. |
long |
longValue() |
Returns the sum() as a long after a narrowing primitive conversion. |
void |
reset() |
Resets variables maintaining the sum to zero. |
double |
sum() |
Returns the current sum. |
double |
sumThenReset() |
|
String |
toString() |
Returns the String representation of the sum() . |
byteValue, shortValue
public DoubleAdder()
public void add(double x)
x
- the value to addpublic double sum()
public void reset()
public double sumThenReset()
sum()
followed by reset()
. This method may apply for example during quiescent points between multithreaded computations. If there are updates concurrent with this method, the returned value is not guaranteed to be the final value occurring before the reset.public String toString()
sum()
.public double doubleValue()
sum()
.doubleValue
in class Number
public long longValue()
sum()
as a long
after a narrowing primitive conversion.public int intValue()
sum()
as an int
after a narrowing primitive conversion.public float floatValue()
sum()
as a float
after a narrowing primitive conversion.floatValue
in class Number
float
.
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/concurrent/atomic/DoubleAdder.html