LongSummaryStatistics

public class LongSummaryStatistics
extends Object implements LongConsumer, IntConsumer

java.lang.Object
   ↳ java.util.LongSummaryStatistics


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.

Summary

Public constructors

LongSummaryStatistics()

Constructs 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 non-empty instance with the specified count, min, max, and sum.

Public methods

void accept(int value)

Records a new int value into the summary information.

void accept(long value)

Records a new long value into the summary information.

void combine(LongSummaryStatistics other)

Combines the state of another LongSummaryStatistics into this one.

final double getAverage()

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, or Long.MIN_VALUE if no values have been recorded

final long getMin()

Returns the minimum value recorded, or Long.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.

String toString()

Returns a non-empty string representation of this object suitable for debugging.

Inherited methods

Public constructors

LongSummaryStatistics

Added in API level 24
public LongSummaryStatistics ()

Constructs an empty instance with zero count, zero sum, Long.MAX_VALUE min, Long.MIN_VALUE max and zero average.

LongSummaryStatistics

Added in API level 24
public LongSummaryStatistics (long count, 
                long min, 
                long max, 
                long sum)

Constructs a non-empty 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

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, and sum = 0.
Parameters
count long: the count of values

min long: the minimum value

max long: the maximum value

sum long: the sum of all values

Throws
IllegalArgumentException if the arguments are inconsistent

Public methods

accept

Added in API level 24
public void accept (int value)

Records a new int value into the summary information.

Parameters
value int: the input value

accept

Added in API level 24
public void accept (long value)

Records a new long value into the summary information.

Parameters
value long: the input value

combine

Added in API level 24
public void combine (LongSummaryStatistics other)

Combines the state of another LongSummaryStatistics into this one.

Parameters
other LongSummaryStatistics: another LongSummaryStatistics

Throws
NullPointerException if other is null

getAverage

Added in API level 24
public final double getAverage ()

Returns the arithmetic mean of values recorded, or zero if no values have been recorded.

Returns
double The arithmetic mean of values, or zero if none

getCount

Added in API level 24
public final long getCount ()

Returns the count of values recorded.

Returns
long the count of values

getMax

Added in API level 24
public final long getMax ()

Returns the maximum value recorded, or Long.MIN_VALUE if no values have been recorded

Returns
long the maximum value, or Long.MIN_VALUE if none

getMin

Added in API level 24
public final long getMin ()

Returns the minimum value recorded, or Long.MAX_VALUE if no values have been recorded.

Returns
long the minimum value, or Long.MAX_VALUE if none

getSum

Added in API level 24
public final long getSum ()

Returns the sum of values recorded, or zero if no values have been recorded.

Returns
long the sum of values, or zero if none

toString

Added in API level 24
public String toString ()

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.

Returns
String a string representation of the object.