Class LongSummaryStatistics
- java.lang.Object
-
- java.util.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 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 sum.
- Since:
- 1.8
Constructor Summary
Constructor | Description |
---|---|
LongSummaryStatistics() | Constructs an empty instance with zero count, zero sum, |
LongSummaryStatistics(long count,
long min,
long max,
long sum) | Constructs a non-empty instance with the specified |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | accept(int value) | Records a new |
void | accept(long value) | Records a new |
void | combine(LongSummaryStatistics other) | Combines the state of another |
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 | getMin() | Returns the minimum value recorded, or |
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. |
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 Detail
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 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, andsum
= 0. - Parameters:
-
count
- the count of values -
min
- the minimum value -
max
- the maximum value -
sum
- the sum of all values - Throws:
-
IllegalArgumentException
- if the arguments are inconsistent - Since:
- 10
Method Detail
accept
public void accept(int value)
Records a new int
value into the summary information.
- Specified by:
-
accept
in interfaceIntConsumer
- Parameters:
-
value
- the input value
accept
public void accept(long value)
Records a new long
value into the summary information.
- Specified by:
-
accept
in interfaceLongConsumer
- Parameters:
-
value
- the input value
combine
public void combine(LongSummaryStatistics other)
Combines the state of another LongSummaryStatistics
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, 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()
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.