Class DoubleSummaryStatistics
 java.lang.Object

 java.util.DoubleSummaryStatistics
 All Implemented Interfaces:
DoubleConsumer
public class DoubleSummaryStatistics extends Object implements DoubleConsumer
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:
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.
 Implementation Note:
 This implementation is not thread safe. However, it is safe to use
Collectors.summarizingDouble()
on a parallel stream, because the parallel implementation ofStream.collect()
provides the necessary partitioning, isolation, and merging of results for safe and efficient parallel execution.  Since:
 1.8
Constructor Summary
Constructor  Description 

DoubleSummaryStatistics()  Constructs an empty instance with zero count, zero sum, 
DoubleSummaryStatistics(long count,
double min,
double max,
double sum)  Constructs a nonempty instance with the specified 
Method Summary
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 
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  getMin()  Returns the minimum recorded value, 
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. 
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Methods declared in interface java.util.function.DoubleConsumer
andThen
Constructor Detail
DoubleSummaryStatistics
public DoubleSummaryStatistics()
Constructs an empty instance with zero count, zero sum, Double.POSITIVE_INFINITY
min, Double.NEGATIVE_INFINITY
max and zero average.
DoubleSummaryStatistics
public DoubleSummaryStatistics(long count, double min, double max, double sum) throws IllegalArgumentException
Constructs a nonempty instance with the specified 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))
 API Note:
 The enforcement of argument correctness means that the retrieved set of recorded values obtained from a
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, andsum
= 0.  Parameters:

count
 the count of values 
min
 the minimum value 
max
 the maximum value 
sum
 the sum of all values  Throws:

IllegalArgumentException
 if the arguments are inconsistent  Since:
 10
Method Detail
accept
public void accept(double value)
Records another value into the summary information.
 Specified by:

accept
in interfaceDoubleConsumer
 Parameters:

value
 the input value
combine
public void combine(DoubleSummaryStatistics other)
Combines the state of another DoubleSummaryStatistics
into this one.
 Parameters:

other
 anotherDoubleSummaryStatistics
 Throws:

NullPointerException
 ifother
is null
getCount
public final long getCount()
Return the count of values recorded.
 Returns:
 the count of values
getSum
public final double getSum()
Returns the sum of values recorded, or zero if no values have been recorded.
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:
 If any recorded value is a NaN, then the final sum will be NaN.
 If the recorded values contain one or more infinities, the sum will be infinite or NaN.
 If the recorded values contain infinities of opposite sign, the sum will be NaN.
 If the recorded values contain infinities of one sign and an intermediate sum overflows to an infinity of the opposite sign, the sum may be NaN.
 API Note:
 Values sorted by increasing absolute magnitude tend to yield more accurate results.
 Returns:
 the sum of values, or zero if none
getMin
public 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. Unlike the numerical comparison operators, this method considers negative zero to be strictly smaller than positive zero.
 Returns:
 the minimum recorded value,
Double.NaN
if any recorded value was NaN orDouble.POSITIVE_INFINITY
if no values were recorded
getMax
public 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. Unlike the numerical comparison operators, this method considers negative zero to be strictly smaller than positive zero.
 Returns:
 the maximum recorded value,
Double.NaN
if any recorded value was NaN orDouble.NEGATIVE_INFINITY
if no values were recorded
getAverage
public final double getAverage()
Returns the arithmetic mean of values recorded, or zero if no values have been recorded.
The computed average can vary numerically and have the special case behavior as computing the sum; see getSum()
for details.
 API Note:
 Values sorted by increasing absolute magnitude tend to yield more accurate results.
 Returns:
 the arithmetic mean of values, or zero if none
toString
public String toString()
Returns a nonempty string representation of this object suitable for debugging. The exact presentation format is unspecified and may vary between implementations and versions.