public
class
DoubleSummaryStatistics
extends Object
implements
DoubleConsumer
| java.lang.Object | |
| ↳ | java.util.DoubleSummaryStatistics |
A state object for collecting statistics such as count, min, max, sum, and average.
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:
Developers
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.
Public constructors | |
|---|---|
DoubleSummaryStatistics()
Construct an empty instance with zero count, zero sum,
|
|
Public methods | |
|---|---|
void
|
accept(double value)
Records another value into the summary information. |
void
|
combine(DoubleSummaryStatistics other)
Combines the state of another |
final
double
|
getAverage()
Returns the arithmetic mean of values recorded, or zero if no values have been recorded. |
final
long
|
getCount()
Return the count of values recorded. |
final
double
|
getMax()
Returns the maximum recorded value, |
final
double
|
getMin()
Returns the minimum recorded value, |
final
double
|
getSum()
Returns the sum of values recorded, or zero if no values have been recorded. |
String
|
toString()
Returns a string representation of the object. Returns a non-empty string representation of this object suitable for debugging. |
Inherited methods | |
|---|---|
 From
class
java.lang.Object
| |
From
interface
java.util.function.DoubleConsumer
| |
DoubleSummaryStatistics ()
Construct an empty instance with zero count, zero sum,
Double.POSITIVE_INFINITY min, Double.NEGATIVE_INFINITY
max and zero average.
void accept (double value)
Records another value into the summary information.
| Parameters | |
|---|---|
value |
double:
the input value
|
void combine (DoubleSummaryStatistics other)
Combines the state of another DoubleSummaryStatistics into this
one.
| Parameters | |
|---|---|
other |
DoubleSummaryStatistics:
another DoubleSummaryStatistics |
| Throws | |
|---|---|
NullPointerException |
if other is null
|
double getAverage ()
Returns the arithmetic mean of values recorded, or zero if no values have been recorded. If any recorded value is a NaN or the sum is at any point a NaN then the average will be code NaN.
The average returned can vary depending upon the order in
which values are recorded.
This method may be implemented using compensated summation or
other technique to reduce the error bound in the numerical sum used to compute the average.
| Returns | |
|---|---|
double |
the arithmetic mean of values, or zero if none |
long getCount ()
Return the count of values recorded.
| Returns | |
|---|---|
long |
the count of values |
double getMax ()
Returns the maximum recorded value, 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.
| Returns | |
|---|---|
double |
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. Unlike the numerical comparison operators, this method
considers negative zero to be strictly smaller than positive zero.
| Returns | |
|---|---|
double |
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. If any recorded value is a NaN or the sum is at any point a NaN then the sum will be NaN.
The value of a floating-point 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.
| Returns | |
|---|---|
double |
the sum of values, or zero if none |
String toString ()
Returns a string representation of the object. In general, the
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())
| Returns | |
|---|---|
String |
a string representation of the object. |