Top Description Fields Constructors Methods
java.util

public Class LongSummaryStatistics

extends Object
implements LongConsumer, IntConsumer
Class Inheritance
All Implemented Interfaces
java.util.function.IntConsumer, java.util.function.LongConsumer
Annotations
@SuppressWarnings:overloads
Imports
java.util.function.IntConsumer, .LongConsumer, java.util.stream.Collector
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 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 count or the sum.

Since
1.8

Field Summary

Modifier and TypeField and Description
private long
count

private long
max

private long
min

private long
sum

Constructor Summary

AccessConstructor and Description
public
LongSummaryStatistics()

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

public
LongSummaryStatistics(long
the count of values
count, long
the minimum value
min, long
the maximum value
max, long
the sum of all values
sum)

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

Method Summary

Modifier and TypeMethod and Description
public void
accept(int
the input value
value)

Implements java.util.function.IntConsumer.accept.

Records a new int value into the summary information.

public void
accept(long
the input value
value)

Implements java.util.function.LongConsumer.accept.

Records a new long value into the summary information.

public void
combine(LongSummaryStatistics
another LongSummaryStatistics
other)

Combines the state of another LongSummaryStatistics into this one.

public final double

Returns:

The arithmetic mean of values, or zero if none
getAverage()

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

public final long

Returns:

the count of values
getCount()

Returns the count of values recorded.

public final long

Returns:

the maximum value, or Long.MIN_VALUE if none
getMax()

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

public final long

Returns:

the minimum value, or Long.MAX_VALUE if none
getMin()

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

public final long

Returns:

the sum of values, or zero if none
getSum()

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

public String
toString()

Overrides java.lang.Object.toString.

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

Inherited from java.lang.Object:
cloneequalsfinalizegetClasshashCodenotifynotifyAllwaitwaitwait

Field Detail

countback to summary
private long count
maxback to summary
private long max
minback to summary
private long min
sumback to summary
private long sum

Constructor Detail

LongSummaryStatisticsback to summary
public LongSummaryStatistics()

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

LongSummaryStatisticsback to summary
public LongSummaryStatistics(long count, long min, long max, long sum) throws IllegalArgumentException

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

Exceptions
IllegalArgumentException:
if the arguments are inconsistent
Since
10

Method Detail

acceptback to summary
public void accept(int value)

Implements java.util.function.IntConsumer.accept.

Records a new int value into the summary information.

Parameters
value:int

the input value

Annotations
@Override
acceptback to summary
public void accept(long value)

Implements java.util.function.LongConsumer.accept.

Records a new long value into the summary information.

Parameters
value:long

the input value

Annotations
@Override
combineback to summary
public void combine(LongSummaryStatistics other)

Combines the state of another LongSummaryStatistics into this one.

Parameters
other:LongSummaryStatistics

another LongSummaryStatistics

Exceptions
NullPointerException:
if other is null
getAverageback to summary
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

getCountback to summary
public final long getCount()

Returns the count of values recorded.

Returns:long

the count of values

getMaxback to summary
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

getMinback to summary
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

getSumback to summary
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

toStringback to summary
public String toString()

Overrides java.lang.Object.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

Doc from java.lang.Object.toString.

a string representation of the object

Annotations
@Override