java8.util

Class IntSummaryStatistics

java.lang.Object

java8.util.IntSummaryStatistics

All Implemented Interfaces:

IntConsumer

public class IntSummaryStatistics
extends java.lang.Object
implements 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 ints with:

 
 IntSummaryStatistics stats = intStream.collect(IntSummaryStatistics::new,
                                                IntSummaryStatistics::accept,
                                                IntSummaryStatistics::combine);
 

IntSummaryStatistics can be used as a reduction target for a stream. For example:

 
 IntSummaryStatistics stats = people.stream()
                                    .collect(Collectors.summarizingInt(Person::getDependents));

This computes, in a single pass, the count of people, as well as the minimum, maximum, sum, and average of their number of dependents.

Implementation Note:
This implementation is not thread safe. However, it is safe to use Collectors.toIntStatistics() 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

Constructor Summary

Constructors

Constructor and Description
IntSummaryStatistics() Construct an empty instance with zero count, zero sum, Integer.MAX_VALUE min, Integer.MIN_VALUE max and zero average.

Method Summary

Modifier and Type	Method and Description
void	accept(int value) Records a new value into the summary information
void	combine(IntSummaryStatistics other) Combines the state of another IntSummaryStatistics 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.
int	getMax() Returns the maximum value recorded, or Integer.MIN_VALUE if no values have been recorded.
int	getMin() Returns the minimum value recorded, or Integer.MAX_VALUE if no values have been recorded.
long	getSum() Returns the sum of values recorded, or zero if no values have been recorded.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

IntSummaryStatistics

public IntSummaryStatistics()

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

Method Detail

accept

public void accept(int value)

Records a new value into the summary information

Specified by:

accept in interface IntConsumer

Parameters:

value - the input value

combine

public void combine(IntSummaryStatistics other)

Combines the state of another IntSummaryStatistics into this one.

Parameters:

other - another IntSummaryStatistics

Throws:

java.lang.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 int getMin()

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

Returns:

the minimum value, or Integer.MAX_VALUE if none

getMax

public final int getMax()

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

Returns:

the maximum value, or Integer.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 java.lang.String toString()

Overrides:

toString in class java.lang.Object