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. This implementation does not check for overflow of the count.
Constructor | Description |
---|---|
DoubleSummaryStatistics() |
Constructs an empty instance with zero count, zero sum, Double.POSITIVE_INFINITY min, Double.NEGATIVE_INFINITY max and zero average. |
DoubleSummaryStatistics |
Constructs a non-empty instance with the specified count , min , max , and sum . |
Modifier and Type | Method | Description |
---|---|---|
void |
accept |
Records another value into the summary information. |
void |
combine |
Combines the state of another DoubleSummaryStatistics into this one. |
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, Double.NaN if any recorded value was NaN or Double.NEGATIVE_INFINITY if no values were recorded. |
final double |
getMin() |
Returns the minimum recorded value, Double.NaN if any recorded value was NaN or Double.POSITIVE_INFINITY if no values were recorded. |
final double |
getSum() |
Returns the sum of values recorded, or zero if no values have been recorded. |
String |
toString() |
Returns a non-empty string representation of this object suitable for debugging. |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
andThen
public DoubleSummaryStatistics()
Double.POSITIVE_INFINITY
min, Double.NEGATIVE_INFINITY
max and zero average.public DoubleSummaryStatistics(long count, double min, double max, double sum) throws IllegalArgumentException
count
, min
, max
, and sum
. If count
is zero then the remaining arguments are ignored and an empty instance is constructed.
If the arguments are inconsistent then an IllegalArgumentException
is thrown. The necessary consistent argument conditions are:
count >= 0
(min <= max && !isNaN(sum)) || (isNaN(min) && isNaN(max) && isNaN(sum))
DoubleSummaryStatistics
source instance may not be a legal set of arguments for this constructor due to arithmetic overflow of the source's recorded count of values. The consistent argument conditions are not sufficient to prevent the creation of an internally inconsistent instance. An example of such a state would be an instance with: count
= 2, min
= 1, max
= 2, and sum
= 0.count
- the count of valuesmin
- the minimum valuemax
- the maximum valuesum
- the sum of all valuesIllegalArgumentException
- if the arguments are inconsistentpublic 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 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. 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 non-finite sum being computed. This can occur even if the all the recorded values being summed are finite. If any recorded value is non-finite, the sum will be non-finite:
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.
public String toString()
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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/DoubleSummaryStatistics.html