Spec-Zone .ru
спецификации, руководства, описания, API
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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.toDoubleSummaryStatistics(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.toDoubleStatistics()
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 and Description |
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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 and Description |
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void |
accept(double value)
Records another value into the summary information.
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void |
combine(DoubleSummaryStatistics other)
Combines the state of another
DoubleSummaryStatistics into this
one. |
double |
getAverage()
Returns the average of values recorded, or zero if no values have been
recorded.
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long |
getCount()
Return the count of values recorded.
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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.
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String |
toString()
Returns a string representation of the object.
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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()
NaN
or the sum is at any point a NaN
then the
sum will be NaN
.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()
NaN
or the sum is at any point a NaN
then the
average will be NaN
.public String toString()
toString
method returns a string that
"textually represents" this object. The result should
be a concise but informative representation that is easy for a
person to read.
It is recommended that all subclasses override this method.
The toString
method for class Object
returns a string consisting of the name of the class of which the
object is an instance, the at-sign character `@
', and
the unsigned hexadecimal representation of the hash code of the
object. In other words, this method returns a string equal to the
value of:
Returns a non-empty string representation of this object suitable for debugging. The exact presentation format is unspecified and may vary between implementations and versions.getClass().getName() + '@' + Integer.toHexString(hashCode())
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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