Class LongSummaryStatistics

All Implemented Interfaces:
IntConsumer, LongConsumer 

public class LongSummaryStatistics
extends Object
implements LongConsumer, IntConsumer

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 Stream.collect(Collector) 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.toLongStatistics() 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 sum.

Since:
1.8

Constructors

Constructor and Description
LongSummaryStatistics()

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

Methods

Modifier and Type Method and Description
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.
double getAverage()

Returns the arithmetic mean of values recorded, or zero if no values have been recorded.
long getCount()

Returns the count of values recorded.
long getMax()

Returns the maximum value recorded, or Long.MIN_VALUE if no values have been recorded
long getMin()

Returns the minimum value recorded, or Long.MAX_VALUE if no values have been recorded.
long getSum()

Returns the sum of values recorded, or zero if no values have been recorded.
String toString()

Returns a string representation of the object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.function.LongConsumer

andThen

Methods inherited from interface java.util.function.IntConsumer

andThen

Constructors

LongSummaryStatistics

public LongSummaryStatistics()

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

Methods

accept

public void accept(int value)

Records a new int value into the summary information.

Specified by:
accept in interface IntConsumer
Parameters:
value - the input value

accept

public void accept(long value)

Records a new long value into the summary information.

Specified by:
accept in interface LongConsumer
Parameters:
value - the input value

combine

public void combine(LongSummaryStatistics other)

Combines the state of another LongSummaryStatistics into this one.

Parameters:
other - another LongSummaryStatistics
Throws:
NullPointerException - if other 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, or Long.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, or Long.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

public String toString()

Description copied from class: Object

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: 

getClass().getName() + '@' + Integer.toHexString(hashCode())
Overrides:
toString in class Object
Returns:
a string representation of the object.

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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/javase/8/docs/api/java/util/LongSummaryStatistics.html