DoubleConsumer
public class DoubleSummaryStatistics extends Object implements DoubleConsumer
This class is designed to work with (though does not require) streams. For example, you can compute summary statistics on a stream of doubles with:
DoubleSummaryStatistics stats = doubleStream.collect(DoubleSummaryStatistics::new,
DoubleSummaryStatistics::accept,
DoubleSummaryStatistics::combine);
DoubleSummaryStatistics
can be used as a
reduction
target for a stream. For example:
DoubleSummaryStatistics stats = people.stream()
.collect(Collectors.summarizingDouble(Person::getWeight));
This computes, in a single pass, the count of people, as well as the minimum,
maximum, sum, and average of their weights.Collectors.summarizingDouble()
on a parallel stream, because the parallel
implementation of Stream.collect()
provides the necessary partitioning, isolation, and merging of results for
safe and efficient parallel execution.Constructor  Description 

DoubleSummaryStatistics() 
Construct an empty instance with zero count, zero sum,
Double.POSITIVE_INFINITY min, Double.NEGATIVE_INFINITY
max and zero average. 
Modifier and Type  Method  Description 

void 
accept(double value) 
Records another value into the summary information.

void 
combine(DoubleSummaryStatistics other) 
Combines the state of another
DoubleSummaryStatistics into this
one. 
double 
getAverage() 
Returns the arithmetic mean of values recorded, or zero if no
values have been recorded.

long 
getCount() 
Return the count of values recorded.

double 
getMax() 
Returns the maximum recorded value,
Double.NaN if any recorded
value was NaN or Double.NEGATIVE_INFINITY if no values were
recorded. 
double 
getMin() 
Returns the minimum recorded value,
Double.NaN if any recorded
value was NaN or Double.POSITIVE_INFINITY if no values were
recorded. 
double 
getSum() 
Returns the sum of values recorded, or zero if no values have been
recorded.

String 
toString() 
Returns a nonempty string representation of this object suitable for
debugging.

andThen
public DoubleSummaryStatistics()
Double.POSITIVE_INFINITY
min, Double.NEGATIVE_INFINITY
max and zero average.public void accept(double value)
accept
in interface DoubleConsumer
value
 the input valuepublic void combine(DoubleSummaryStatistics other)
DoubleSummaryStatistics
into this
one.other
 another DoubleSummaryStatistics
NullPointerException
 if other
is nullpublic final long getCount()
public final double getSum()
The value of a floatingpoint sum is a function both of the
input values as well as the order of addition operations. The
order of addition operations of this method is intentionally
not defined to allow for implementation flexibility to improve
the speed and accuracy of the computed result.
In particular, this method may be implemented using compensated
summation or other technique to reduce the error bound in the
numerical sum compared to a simple summation of double
values.
Because of the unspecified order of operations and the
possibility of using differing summation schemes, the output of
this method may vary on the same input values.
Various conditions can result in a nonfinite sum being computed. This can occur even if the all the recorded values being summed are finite. If any recorded value is nonfinite, the sum will be nonfinite:
public final double getMin()
Double.NaN
if any recorded
value was NaN or Double.POSITIVE_INFINITY
if no values were
recorded. Unlike the numerical comparison operators, this method
considers negative zero to be strictly smaller than positive zero.Double.NaN
if any recorded
value was NaN or Double.POSITIVE_INFINITY
if no values were
recordedpublic final double getMax()
Double.NaN
if any recorded
value was NaN or Double.NEGATIVE_INFINITY
if no values were
recorded. Unlike the numerical comparison operators, this method
considers negative zero to be strictly smaller than positive zero.Double.NaN
if any recorded
value was NaN or Double.NEGATIVE_INFINITY
if no values were
recordedpublic final double getAverage()
The computed average can vary numerically and have the
special case behavior as computing the sum; see getSum()
for details.
Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developertargeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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