Class LongSummaryStatistics
java.lang.Object
java.util.LongSummaryStatistics
 All Implemented Interfaces:
IntConsumer
,LongConsumer
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 longs with:
LongSummaryStatistics stats = longStream.collect(LongSummaryStatistics::new,
LongSummaryStatistics::accept,
LongSummaryStatistics::combine);
LongSummaryStatistics
can be used as a
reduction
target for a stream. For example:
LongSummaryStatistics stats = people.stream()
.collect(Collectors.summarizingLong(Person::getAge));
This computes, in a single pass, the count of people, as well as the minimum,
maximum, sum, and average of their ages. Implementation Note:
 This implementation is not thread safe. However, it is safe to use
Collectors.summarizingLong()
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.This implementation does not check for overflow of the count or the sum.
 Since:
 1.8

Constructor Summary
ConstructorDescriptionConstructs an empty instance with zero count, zero sum,Long.MAX_VALUE
min,Long.MIN_VALUE
max and zero average.LongSummaryStatistics
(long count, long min, long max, long sum) Constructs a nonempty instance with the specifiedcount
,min
,max
, andsum
. 
Method Summary
Modifier and TypeMethodDescriptionvoid
accept
(int value) Records a newint
value into the summary information.void
accept
(long value) Records a newlong
value into the summary information.void
combine
(LongSummaryStatistics other) Combines the state of anotherLongSummaryStatistics
into this one.final double
Returns the arithmetic mean of values recorded, or zero if no values have been recorded.final long
getCount()
Returns the count of values recorded.final long
getMax()
Returns the maximum value recorded, orLong.MIN_VALUE
if no values have been recordedfinal long
getMin()
Returns the minimum value recorded, orLong.MAX_VALUE
if no values have been recorded.final long
getSum()
Returns the sum of values recorded, or zero if no values have been recorded.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.IntConsumer
andThen
Methods declared in interface java.util.function.LongConsumer
andThen

Constructor Details

LongSummaryStatistics
public LongSummaryStatistics()Constructs an empty instance with zero count, zero sum,Long.MAX_VALUE
min,Long.MIN_VALUE
max and zero average. 
LongSummaryStatistics
public LongSummaryStatistics(long count, long min, long max, long sum) throws IllegalArgumentException Constructs a nonempty instance with the specifiedcount
,min
,max
, andsum
.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
 API Note:
 The enforcement of argument correctness means that the retrieved set of
recorded values obtained from a
LongSummaryStatistics
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 valuesmin
 the minimum valuemax
 the maximum valuesum
 the sum of all values Throws:
IllegalArgumentException
 if the arguments are inconsistent Since:
 10


Method Details

accept
public void accept(int value) Records a newint
value into the summary information. Specified by:
accept
in interfaceIntConsumer
 Parameters:
value
 the input value

accept
public void accept(long value) Records a newlong
value into the summary information. Specified by:
accept
in interfaceLongConsumer
 Parameters:
value
 the input value

combine
Combines the state of anotherLongSummaryStatistics
into this one. Parameters:
other
 anotherLongSummaryStatistics
 Throws:
NullPointerException
 ifother
is null

getCount
public final long getCount()Returns the count of values recorded. Returns:
 the count of values

getSum
public final long getSum()Returns the sum of values recorded, or zero if no values have been recorded. Returns:
 the sum of values, or zero if none

getMin
public final long getMin()Returns the minimum value recorded, orLong.MAX_VALUE
if no values have been recorded. Returns:
 the minimum value, or
Long.MAX_VALUE
if none

getMax
public final long getMax()Returns the maximum value recorded, orLong.MIN_VALUE
if no values have been recorded Returns:
 the maximum value, or
Long.MIN_VALUE
if none

getAverage
public final double getAverage()Returns the arithmetic mean of values recorded, or zero if no values have been recorded. Returns:
 The arithmetic mean of values, or zero if none

toString
