LongSummaryStatistics

AI-generated Key Takeaways

• LongSummaryStatistics is a state object used for collecting statistics on a stream of long values, such as count, min, max, sum, and average.

• It can be used as a reduction target for streams, allowing efficient computation of statistics in a single pass.

• This class provides methods to record values, combine statistics from multiple LongSummaryStatistics objects, and retrieve the calculated statistics.

• LongSummaryStatistics is designed to work seamlessly with Java streams, simplifying the process of gathering summary data from collections of long values.

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) {@linkplain java.util.stream 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 {@linkplain java.util.stream.Stream#collect(Collector)} reduction} target for a {@linkplain java.util.stream.Stream 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.

Public Constructor Summary

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

Public Method Summary

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 string containing a concise, human-readable description of this object.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

From interface java.util.function.LongConsumer

abstract void	accept(long value) Performs this operation on the given argument.
LongConsumer	andThen(LongConsumer after) Returns a composed LongConsumer that performs, in sequence, this operation followed by the after operation.

From interface java.util.function.IntConsumer

abstract void	accept(int value) Performs this operation on the given argument.
IntConsumer	andThen(IntConsumer after) Returns a composed IntConsumer that performs, in sequence, this operation followed by the after operation.

Public Constructors

public LongSummaryStatistics ()

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

Public Methods

public void accept (int value)

Records a new int value into the summary information.

Parameters

value	the input value

public void accept (long value)

Records a new long value into the summary information.

Parameters

value	the input value

public void combine (LongSummaryStatistics other)

Combines the state of another LongSummaryStatistics into this one.

Parameters

other	another LongSummaryStatistics

Throws

NullPointerException	if other is null

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

public final long getCount ()

Returns the count of values recorded.

Returns

• the count of values

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

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

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

public String toString ()

Returns a string containing a concise, human-readable description of this object. Subclasses are encouraged to override this method and provide an implementation that takes into account the object's type and data. The default implementation is equivalent to the following expression:

   getClass().getName() + '@' + Integer.toHexString(hashCode())

See Writing a useful toString method if you intend implementing your own toString method.

Returns

• a printable representation of this object.