OpenJDK 1.23 · java.util.stream.LongStream · APIdia, the JavaDoc alternative

Modifier and Type	Class and Description
public static interface	LongStream.Builder A mutable builder for a `LongStream`.
public static interface	LongStream.LongMapMultiConsumer Represents an operation that accepts a `long`-valued argument and a LongConsumer, and returns no result.

Method Summary

Modifier and Type	Method and Description
public boolean	Returns: `true` if either all elements of the stream match the provided predicate or the stream is empty, otherwise `false` allMatch(LongPredicate a non-interfering, stateless predicate to apply to elements of this stream predicate) Returns whether all elements of this stream match the provided predicate.
public boolean	Returns: `true` if any elements of the stream match the provided predicate, otherwise `false` anyMatch(LongPredicate a non-interfering, stateless predicate to apply to elements of this stream predicate) Returns whether any elements of this stream match the provided predicate.
public DoubleStream	Returns: a `DoubleStream` consisting of the elements of this stream, converted to `double` asDoubleStream() Returns a `DoubleStream` consisting of the elements of this stream, converted to `double`.
public OptionalDouble	Returns: an `OptionalDouble` containing the average element of this stream, or an empty optional if the stream is empty average() Returns an `OptionalDouble` describing the arithmetic mean of elements of this stream, or an empty optional if this stream is empty.
public Stream<Long>	Returns: a `Stream` consistent of the elements of this stream, each boxed to `Long` boxed() Returns a `Stream` consisting of the elements of this stream, each boxed to a `Long`.
public static LongStream.Builder	Returns: a stream builder builder() Returns a builder for a `LongStream`.
public < the type of the mutable result container R> R	Returns: the result of the reduction collect(Supplier<R> a function that creates a new mutable result container. For a parallel execution, this function may be called multiple times and must return a fresh value each time. supplier, ObjLongConsumer<R> an associative, non-interfering, stateless function that must fold an element into a result container. accumulator, BiConsumer<R, R> an associative, non-interfering, stateless function that accepts two partial result containers and merges them, which must be compatible with the accumulator function. The combiner function must fold the elements from the second result container into the first result container. combiner) Performs a mutable reduction operation on the elements of this stream.
public static LongStream	Returns: the concatenation of the two input streams concat(LongStream the first stream a, LongStream the second stream b) Creates a lazily concatenated stream whose elements are all the elements of the first stream followed by all the elements of the second stream.
public long	Returns: the count of elements in this stream count() Returns the count of elements in this stream.
public LongStream	Returns: the new stream distinct() Returns a stream consisting of the distinct elements of this stream.
public default LongStream	Returns: the new stream dropWhile(LongPredicate a non-interfering, stateless predicate to apply to elements to determine the longest prefix of elements. predicate) Returns, if this stream is ordered, a stream consisting of the remaining elements of this stream after dropping the longest prefix of elements that match the given predicate.
public static LongStream	Returns: an empty sequential stream empty() Returns an empty sequential `LongStream`.
public LongStream	Returns: the new stream filter(LongPredicate a non-interfering, stateless predicate to apply to each element to determine if it should be included predicate) Returns a stream consisting of the elements of this stream that match the given predicate.
public OptionalLong	Returns: an `OptionalLong` describing some element of this stream, or an empty `OptionalLong` if the stream is empty findAny() Returns an `OptionalLong` describing some element of the stream, or an empty `OptionalLong` if the stream is empty.
public OptionalLong	Returns: an `OptionalLong` describing the first element of this stream, or an empty `OptionalLong` if the stream is empty findFirst() Returns an `OptionalLong` describing the first element of this stream, or an empty `OptionalLong` if the stream is empty.
public LongStream	Returns: the new stream flatMap(LongFunction<? extends LongStream> a non-interfering, stateless function to apply to each element which produces a `LongStream` of new values mapper) Returns a stream consisting of the results of replacing each element of this stream with the contents of a mapped stream produced by applying the provided mapping function to each element.
public void	forEach(LongConsumer a non-interfering action to perform on the elements action) Performs an action for each element of this stream.
public void	forEachOrdered(LongConsumer a non-interfering action to perform on the elements action) Performs an action for each element of this stream, guaranteeing that each element is processed in encounter order for streams that have a defined encounter order.
public static LongStream	Returns: a new infinite sequential unordered `LongStream` generate(LongSupplier the `LongSupplier` for generated elements s) Returns an infinite sequential unordered stream where each element is generated by the provided `LongSupplier`.
public static LongStream	Returns: a new sequential `LongStream` iterate(final long the initial element seed, final LongUnaryOperator a function to be applied to the previous element to produce a new element f) Returns an infinite sequential ordered `LongStream` produced by iterative application of a function `f` to an initial element `seed`, producing a `Stream` consisting of `seed`, `f(seed)`, `f(f(seed))`, etc. The first element (position `0`) in the `LongStream` will be the provided `seed`.
public static LongStream	Returns: a new sequential `LongStream` iterate(long the initial element seed, LongPredicate a predicate to apply to elements to determine when the stream must terminate. hasNext, LongUnaryOperator a function to be applied to the previous element to produce a new element next) Returns a sequential ordered `LongStream` produced by iterative application of the given `next` function to an initial element, conditioned on satisfying the given `hasNext` predicate.
public PrimitiveIterator.OfLong	iterator() Redeclares java.util.stream.BaseStream.iterator. Returns an iterator for the elements of this stream.
public LongStream	Returns: the new stream limit(long the number of elements the stream should be limited to maxSize) Returns a stream consisting of the elements of this stream, truncated to be no longer than `maxSize` in length.
public LongStream	Returns: the new stream map(LongUnaryOperator a non-interfering, stateless function to apply to each element mapper) Returns a stream consisting of the results of applying the given function to the elements of this stream.
public default LongStream	Returns: the new stream mapMulti(LongStream.LongMapMultiConsumer a non-interfering, stateless function that generates replacement elements mapper) Returns a stream consisting of the results of replacing each element of this stream with multiple elements, specifically zero or more elements.
public DoubleStream	Returns: the new stream mapToDouble(LongToDoubleFunction a non-interfering, stateless function to apply to each element mapper) Returns a `DoubleStream` consisting of the results of applying the given function to the elements of this stream.
public IntStream	Returns: the new stream mapToInt(LongToIntFunction a non-interfering, stateless function to apply to each element mapper) Returns an `IntStream` consisting of the results of applying the given function to the elements of this stream.
public < the element type of the new stream U> Stream<U>	Returns: the new stream mapToObj(LongFunction<? extends U> a non-interfering, stateless function to apply to each element mapper) Returns an object-valued `Stream` consisting of the results of applying the given function to the elements of this stream.
public OptionalLong	Returns: an `OptionalLong` containing the maximum element of this stream, or an empty `OptionalLong` if the stream is empty max() Returns an `OptionalLong` describing the maximum element of this stream, or an empty optional if this stream is empty.
public OptionalLong	Returns: an `OptionalLong` containing the minimum element of this stream, or an empty `OptionalLong` if the stream is empty min() Returns an `OptionalLong` describing the minimum element of this stream, or an empty optional if this stream is empty.
public boolean	Returns: `true` if either no elements of the stream match the provided predicate or the stream is empty, otherwise `false` noneMatch(LongPredicate a non-interfering, stateless predicate to apply to elements of this stream predicate) Returns whether no elements of this stream match the provided predicate.
public static LongStream	Returns: a singleton sequential stream of(long the single element t) Returns a sequential `LongStream` containing a single element.
public static LongStream	Returns: the new stream of(long... the elements of the new stream values) Returns a sequential ordered stream whose elements are the specified values.
public LongStream	parallel() Redeclares java.util.stream.BaseStream.parallel. Returns an equivalent stream that is parallel.
public LongStream	Returns: the new stream peek(LongConsumer a non-interfering action to perform on the elements as they are consumed from the stream action) Returns a stream consisting of the elements of this stream, additionally performing the provided action on each element as elements are consumed from the resulting stream.
public static LongStream	Returns: a sequential `LongStream` for the range of `long` elements range(long the (inclusive) initial value startInclusive, final long the exclusive upper bound endExclusive) Returns a sequential ordered `LongStream` from `startInclusive` (inclusive) to `endExclusive` (exclusive) by an incremental step of `1`.
public static LongStream	Returns: a sequential `LongStream` for the range of `long` elements rangeClosed(long the (inclusive) initial value startInclusive, final long the inclusive upper bound endInclusive) Returns a sequential ordered `LongStream` from `startInclusive` (inclusive) to `endInclusive` (inclusive) by an incremental step of `1`.
public long	Returns: the result of the reduction reduce(long the identity value for the accumulating function identity, LongBinaryOperator an associative, non-interfering, stateless function for combining two values op) Performs a reduction on the elements of this stream, using the provided identity value and an associative accumulation function, and returns the reduced value.
public OptionalLong	Returns: the result of the reduction reduce(LongBinaryOperator an associative, non-interfering, stateless function for combining two values op) Performs a reduction on the elements of this stream, using an associative accumulation function, and returns an `OptionalLong` describing the reduced value, if any.
public LongStream	sequential() Redeclares java.util.stream.BaseStream.sequential. Returns an equivalent stream that is sequential.
public LongStream	Returns: the new stream skip(long the number of leading elements to skip n) Returns a stream consisting of the remaining elements of this stream after discarding the first `n` elements of the stream.
public LongStream	Returns: the new stream sorted() Returns a stream consisting of the elements of this stream in sorted order.
public Spliterator.OfLong	spliterator() Redeclares java.util.stream.BaseStream.spliterator. Returns a spliterator for the elements of this stream.
public long	Returns: the sum of elements in this stream sum() Returns the sum of elements in this stream.
public LongSummaryStatistics	Returns: a `LongSummaryStatistics` describing various summary data about the elements of this stream summaryStatistics() Returns a `LongSummaryStatistics` describing various summary data about the elements of this stream.
public default LongStream	Returns: the new stream takeWhile(LongPredicate a non-interfering, stateless predicate to apply to elements to determine the longest prefix of elements. predicate) Returns, if this stream is ordered, a stream consisting of the longest prefix of elements taken from this stream that match the given predicate.
public long[]	Returns: an array containing the elements of this stream toArray() Returns an array containing the elements of this stream.

Inherited from java.util.stream.BaseStream:: close isParallel onClose unordered

Method Detail

allMatch back to summary

allMatch	back to summary
public boolean allMatch(LongPredicate predicate) Returns whether all elements of this stream match the provided predicate. May not evaluate the predicate on all elements if not necessary for determining the result. If the stream is empty then `true` is returned and the predicate is not evaluated. This is a short-circuiting terminal operation. API Note This method evaluates the universal quantification of the predicate over the elements of the stream (for all x P(x)). If the stream is empty, the quantification is said to be vacuously satisfied and is always `true` (regardless of P(x)). Parameters predicate:LongPredicate a non-interfering, stateless predicate to apply to elements of this stream Returns:boolean `true` if either all elements of the stream match the provided predicate or the stream is empty, otherwise `false`

public boolean allMatch(LongPredicate predicate)

Returns whether all elements of this stream match the provided predicate. May not evaluate the predicate on all elements if not necessary for determining the result. If the stream is empty then true is returned and the predicate is not evaluated.

This is a short-circuiting terminal operation.

API Note

This method evaluates the universal quantification of the predicate over the elements of the stream (for all x P(x)). If the stream is empty, the quantification is said to be vacuously satisfied and is always true (regardless of P(x)).

Parameters

predicate:LongPredicate: a non-interfering, stateless predicate to apply to elements of this stream

Returns:boolean

true if either all elements of the stream match the provided predicate or the stream is empty, otherwise false

anyMatch back to summary

anyMatch	back to summary
public boolean anyMatch(LongPredicate predicate) Returns whether any elements of this stream match the provided predicate. May not evaluate the predicate on all elements if not necessary for determining the result. If the stream is empty then `false` is returned and the predicate is not evaluated. This is a short-circuiting terminal operation. API Note This method evaluates the existential quantification of the predicate over the elements of the stream (for some x P(x)). Parameters predicate:LongPredicate a non-interfering, stateless predicate to apply to elements of this stream Returns:boolean `true` if any elements of the stream match the provided predicate, otherwise `false`

public boolean anyMatch(LongPredicate predicate)

Returns whether any elements of this stream match the provided predicate. May not evaluate the predicate on all elements if not necessary for determining the result. If the stream is empty then false is returned and the predicate is not evaluated.

This is a short-circuiting terminal operation.

API Note

This method evaluates the existential quantification of the predicate over the elements of the stream (for some x P(x)).

Parameters

predicate:LongPredicate: a non-interfering, stateless predicate to apply to elements of this stream

Returns:boolean

true if any elements of the stream match the provided predicate, otherwise false

asDoubleStream back to summary

asDoubleStream	back to summary
public DoubleStream asDoubleStream() Returns a `DoubleStream` consisting of the elements of this stream, converted to `double`. This is an intermediate operation. Returns:DoubleStream a `DoubleStream` consisting of the elements of this stream, converted to `double`

public DoubleStream asDoubleStream()

Returns a DoubleStream consisting of the elements of this stream, converted to double.

This is an intermediate operation.

Returns:DoubleStream: a DoubleStream consisting of the elements of this stream, converted to double

average back to summary

average	back to summary
public OptionalDouble average() Returns an `OptionalDouble` describing the arithmetic mean of elements of this stream, or an empty optional if this stream is empty. This is a special case of a reduction. This is a terminal operation. Returns:OptionalDouble an `OptionalDouble` containing the average element of this stream, or an empty optional if the stream is empty

public OptionalDouble average()

Returns an OptionalDouble describing the arithmetic mean of elements of this stream, or an empty optional if this stream is empty. This is a special case of a reduction.

This is a terminal operation.

Returns:OptionalDouble: an OptionalDouble containing the average element of this stream, or an empty optional if the stream is empty

boxed back to summary

boxed	back to summary
public Stream<Long> boxed() Returns a `Stream` consisting of the elements of this stream, each boxed to a `Long`. This is an intermediate operation. Returns:Stream<Long> a `Stream` consistent of the elements of this stream, each boxed to `Long`

public Stream<Long> boxed()

Returns a Stream consisting of the elements of this stream, each boxed to a Long.

This is an intermediate operation.

Returns:Stream<Long>: a Stream consistent of the elements of this stream, each boxed to Long

builder back to summary

builder	back to summary
public static LongStream.Builder builder() Returns a builder for a `LongStream`. Returns:LongStream.Builder a stream builder

public static LongStream.Builder builder()

Returns a builder for a LongStream.

Returns:LongStream.Builder: a stream builder

collect back to summary

collect	back to summary
public <R> R collect(Supplier<R> supplier, ObjLongConsumer<R> accumulator, BiConsumer<R, R> combiner) Performs a mutable reduction operation on the elements of this stream. A mutable reduction is one in which the reduced value is a mutable result container, such as an `ArrayList`, and elements are incorporated by updating the state of the result rather than by replacing the result. This produces a result equivalent to: `R result = supplier.get(); for (long element : this stream) accumulator.accept(result, element); return result;` Like `reduce(long, LongBinaryOperator)`, `collect` operations can be parallelized without requiring additional synchronization. This is a terminal operation. Parameters <R> the type of the mutable result container supplier:Supplier<R> a function that creates a new mutable result container. For a parallel execution, this function may be called multiple times and must return a fresh value each time. accumulator:ObjLongConsumer<R> an associative, non-interfering, stateless function that must fold an element into a result container. combiner:BiConsumer<R, R> an associative, non-interfering, stateless function that accepts two partial result containers and merges them, which must be compatible with the accumulator function. The combiner function must fold the elements from the second result container into the first result container. Returns:R the result of the reduction See Also `Stream#collect(Supplier, BiConsumer, BiConsumer)`

public <R> R collect(Supplier<R> supplier, ObjLongConsumer<R> accumulator, BiConsumer<R, R> combiner)

Performs a mutable reduction operation on the elements of this stream. A mutable reduction is one in which the reduced value is a mutable result container, such as an ArrayList, and elements are incorporated by updating the state of the result rather than by replacing the result. This produces a result equivalent to:

R result = supplier.get();
    for (long element : this stream)
        accumulator.accept(result, element);
    return result;

Like reduce(long, LongBinaryOperator), collect operations can be parallelized without requiring additional synchronization.

This is a terminal operation.

Parameters

<R>: the type of the mutable result container
supplier:Supplier<R>: a function that creates a new mutable result container. For a parallel execution, this function may be called multiple times and must return a fresh value each time.
accumulator:ObjLongConsumer<R>: an associative, non-interfering, stateless function that must fold an element into a result container.
combiner:BiConsumer<R, R>: an associative, non-interfering, stateless function that accepts two partial result containers and merges them, which must be compatible with the accumulator function. The combiner function must fold the elements from the second result container into the first result container.

Returns:R

the result of the reduction

concat back to summary

concat	back to summary
public static LongStream concat(LongStream a, LongStream b) Creates a lazily concatenated stream whose elements are all the elements of the first stream followed by all the elements of the second stream. The resulting stream is ordered if both of the input streams are ordered, and parallel if either of the input streams is parallel. When the resulting stream is closed, the close handlers for both input streams are invoked. This method operates on the two input streams and binds each stream to its source. As a result subsequent modifications to an input stream source may not be reflected in the concatenated stream result. Implementation Note Use caution when constructing streams from repeated concatenation. Accessing an element of a deeply concatenated stream can result in deep call chains, or even `StackOverflowError`. API Note To preserve optimization opportunities this method binds each stream to its source and accepts only two streams as parameters. For example, the exact size of the concatenated stream source can be computed if the exact size of each input stream source is known. To concatenate more streams without binding, or without nested calls to this method, try creating a stream of streams and flat-mapping with the identity function, for example: `LongStream concat = Stream.of(s1, s2, s3, s4).flatMapToLong(s -> s);` Parameters a:LongStream the first stream b:LongStream the second stream Returns:LongStream the concatenation of the two input streams

public static LongStream concat(LongStream a, LongStream b)

Creates a lazily concatenated stream whose elements are all the elements of the first stream followed by all the elements of the second stream. The resulting stream is ordered if both of the input streams are ordered, and parallel if either of the input streams is parallel. When the resulting stream is closed, the close handlers for both input streams are invoked.

This method operates on the two input streams and binds each stream to its source. As a result subsequent modifications to an input stream source may not be reflected in the concatenated stream result.

Implementation Note

Use caution when constructing streams from repeated concatenation. Accessing an element of a deeply concatenated stream can result in deep call chains, or even StackOverflowError.

API Note

To preserve optimization opportunities this method binds each stream to its source and accepts only two streams as parameters. For example, the exact size of the concatenated stream source can be computed if the exact size of each input stream source is known. To concatenate more streams without binding, or without nested calls to this method, try creating a stream of streams and flat-mapping with the identity function, for example:

LongStream concat = Stream.of(s1, s2, s3, s4).flatMapToLong(s -> s);

Parameters

a:LongStream: the first stream
b:LongStream: the second stream

Returns:LongStream

the concatenation of the two input streams

count back to summary

count	back to summary
public long count() Returns the count of elements in this stream. This is a special case of a reduction and is equivalent to: `return map(e -> 1L).sum();` This is a terminal operation. API Note An implementation may choose to not execute the stream pipeline (either sequentially or in parallel) if it is capable of computing the count directly from the stream source. In such cases no source elements will be traversed and no intermediate operations will be evaluated. Behavioral parameters with side-effects, which are strongly discouraged except for harmless cases such as debugging, may be affected. For example, consider the following stream: `LongStream s = LongStream.of(1, 2, 3, 4); long count = s.peek(System.out::println).count();` The number of elements covered by the stream source is known and the intermediate operation, `peek`, does not inject into or remove elements from the stream (as may be the case for `flatMap` or `filter` operations). Thus the count is 4 and there is no need to execute the pipeline and, as a side-effect, print out the elements. Returns:long the count of elements in this stream

public long count()

Returns the count of elements in this stream. This is a special case of a reduction and is equivalent to:

return map(e -> 1L).sum();

This is a terminal operation.

API Note

An implementation may choose to not execute the stream pipeline (either sequentially or in parallel) if it is capable of computing the count directly from the stream source. In such cases no source elements will be traversed and no intermediate operations will be evaluated. Behavioral parameters with side-effects, which are strongly discouraged except for harmless cases such as debugging, may be affected. For example, consider the following stream:

LongStream s = LongStream.of(1, 2, 3, 4);
    long count = s.peek(System.out::println).count();

The number of elements covered by the stream source is known and the intermediate operation, peek, does not inject into or remove elements from the stream (as may be the case for flatMap or filter operations). Thus the count is 4 and there is no need to execute the pipeline and, as a side-effect, print out the elements.

Returns:long: the count of elements in this stream

distinct	back to summary
public LongStream distinct() Returns a stream consisting of the distinct elements of this stream. This is a stateful intermediate operation. Returns:LongStream the new stream

distinct

back to summary

public LongStream distinct()

Returns a stream consisting of the distinct elements of this stream.

This is a stateful intermediate operation.

Returns:LongStream: the new stream

dropWhile back to summary

dropWhile	back to summary
public default LongStream dropWhile(LongPredicate predicate) Returns, if this stream is ordered, a stream consisting of the remaining elements of this stream after dropping the longest prefix of elements that match the given predicate. Otherwise returns, if this stream is unordered, a stream consisting of the remaining elements of this stream after dropping a subset of elements that match the given predicate. If this stream is ordered then the longest prefix is a contiguous sequence of elements of this stream that match the given predicate. The first element of the sequence is the first element of this stream, and the element immediately following the last element of the sequence does not match the given predicate. If this stream is unordered, and some (but not all) elements of this stream match the given predicate, then the behavior of this operation is nondeterministic; it is free to drop any subset of matching elements (which includes the empty set). Independent of whether this stream is ordered or unordered if all elements of this stream match the given predicate then this operation drops all elements (the result is an empty stream), or if no elements of the stream match the given predicate then no elements are dropped (the result is the same as the input). This is a stateful intermediate operation. Implementation Specification The default implementation obtains the `spliterator` of this stream, wraps that spliterator so as to support the semantics of this operation on traversal, and returns a new stream associated with the wrapped spliterator. The returned stream preserves the execution characteristics of this stream (namely parallel or sequential execution as per `isParallel()`) but the wrapped spliterator may choose to not support splitting. When the returned stream is closed, the close handlers for both the returned and this stream are invoked. API Note While `dropWhile()` is generally a cheap operation on sequential stream pipelines, it can be quite expensive on ordered parallel pipelines, since the operation is constrained to return not just any valid prefix, but the longest prefix of elements in the encounter order. Using an unordered stream source (such as `generate(LongSupplier)`) or removing the ordering constraint with `unordered()` may result in significant speedups of `dropWhile()` in parallel pipelines, if the semantics of your situation permit. If consistency with encounter order is required, and you are experiencing poor performance or memory utilization with `dropWhile()` in parallel pipelines, switching to sequential execution with `sequential()` may improve performance. Parameters predicate:LongPredicate a non-interfering, stateless predicate to apply to elements to determine the longest prefix of elements. Returns:LongStream the new stream Since 9

public default LongStream dropWhile(LongPredicate predicate)

Returns, if this stream is ordered, a stream consisting of the remaining elements of this stream after dropping the longest prefix of elements that match the given predicate. Otherwise returns, if this stream is unordered, a stream consisting of the remaining elements of this stream after dropping a subset of elements that match the given predicate.

If this stream is ordered then the longest prefix is a contiguous sequence of elements of this stream that match the given predicate. The first element of the sequence is the first element of this stream, and the element immediately following the last element of the sequence does not match the given predicate.

If this stream is unordered, and some (but not all) elements of this stream match the given predicate, then the behavior of this operation is nondeterministic; it is free to drop any subset of matching elements (which includes the empty set).

Independent of whether this stream is ordered or unordered if all elements of this stream match the given predicate then this operation drops all elements (the result is an empty stream), or if no elements of the stream match the given predicate then no elements are dropped (the result is the same as the input).

This is a stateful intermediate operation.

Implementation Specification

The default implementation obtains the spliterator of this stream, wraps that spliterator so as to support the semantics of this operation on traversal, and returns a new stream associated with the wrapped spliterator. The returned stream preserves the execution characteristics of this stream (namely parallel or sequential execution as per isParallel()) but the wrapped spliterator may choose to not support splitting. When the returned stream is closed, the close handlers for both the returned and this stream are invoked.

API Note

While dropWhile() is generally a cheap operation on sequential stream pipelines, it can be quite expensive on ordered parallel pipelines, since the operation is constrained to return not just any valid prefix, but the longest prefix of elements in the encounter order. Using an unordered stream source (such as generate(LongSupplier)) or removing the ordering constraint with unordered() may result in significant speedups of dropWhile() in parallel pipelines, if the semantics of your situation permit. If consistency with encounter order is required, and you are experiencing poor performance or memory utilization with dropWhile() in parallel pipelines, switching to sequential execution with sequential() may improve performance.

Parameters

predicate:LongPredicate: a non-interfering, stateless predicate to apply to elements to determine the longest prefix of elements.

Returns:LongStream

the new stream

Since

empty back to summary

empty	back to summary
public static LongStream empty() Returns an empty sequential `LongStream`. Returns:LongStream an empty sequential stream

public static LongStream empty()

Returns an empty sequential LongStream.

Returns:LongStream: an empty sequential stream

filter	back to summary
public LongStream filter(LongPredicate predicate) Returns a stream consisting of the elements of this stream that match the given predicate. This is an intermediate operation. Parameters predicate:LongPredicate a non-interfering, stateless predicate to apply to each element to determine if it should be included Returns:LongStream the new stream

filter

back to summary

public LongStream filter(LongPredicate predicate)

Returns a stream consisting of the elements of this stream that match the given predicate.

This is an intermediate operation.

Parameters

predicate:LongPredicate: a non-interfering, stateless predicate to apply to each element to determine if it should be included

Returns:LongStream

the new stream

findAny back to summary

findAny	back to summary
public OptionalLong findAny() Returns an `OptionalLong` describing some element of the stream, or an empty `OptionalLong` if the stream is empty. This is a short-circuiting terminal operation. The behavior of this operation is explicitly nondeterministic; it is free to select any element in the stream. This is to allow for maximal performance in parallel operations; the cost is that multiple invocations on the same source may not return the same result. (If a stable result is desired, use `findFirst()` instead.) Returns:OptionalLong an `OptionalLong` describing some element of this stream, or an empty `OptionalLong` if the stream is empty See Also `findFirst()`

public OptionalLong findAny()

Returns an OptionalLong describing some element of the stream, or an empty OptionalLong if the stream is empty.

This is a short-circuiting terminal operation.

The behavior of this operation is explicitly nondeterministic; it is free to select any element in the stream. This is to allow for maximal performance in parallel operations; the cost is that multiple invocations on the same source may not return the same result. (If a stable result is desired, use findFirst() instead.)

Returns:OptionalLong: an OptionalLong describing some element of this stream, or an empty OptionalLong if the stream is empty
See Also: findFirst()

findFirst back to summary

findFirst	back to summary
public OptionalLong findFirst() Returns an `OptionalLong` describing the first element of this stream, or an empty `OptionalLong` if the stream is empty. If the stream has no encounter order, then any element may be returned. This is a short-circuiting terminal operation. Returns:OptionalLong an `OptionalLong` describing the first element of this stream, or an empty `OptionalLong` if the stream is empty

public OptionalLong findFirst()

Returns an OptionalLong describing the first element of this stream, or an empty OptionalLong if the stream is empty. If the stream has no encounter order, then any element may be returned.

This is a short-circuiting terminal operation.

Returns:OptionalLong: an OptionalLong describing the first element of this stream, or an empty OptionalLong if the stream is empty

flatMap back to summary

flatMap	back to summary
public LongStream flatMap(LongFunction<? extends LongStream> mapper) Returns a stream consisting of the results of replacing each element of this stream with the contents of a mapped stream produced by applying the provided mapping function to each element. Each mapped stream is `closed` after its contents have been placed into this stream. (If a mapped stream is `null` an empty stream is used, instead.) This is an intermediate operation. Parameters mapper:LongFunction<? extends LongStream> a non-interfering, stateless function to apply to each element which produces a `LongStream` of new values Returns:LongStream the new stream See Also `Stream#flatMap(Function)`

public LongStream flatMap(LongFunction<? extends LongStream> mapper)

Returns a stream consisting of the results of replacing each element of this stream with the contents of a mapped stream produced by applying the provided mapping function to each element. Each mapped stream is closed after its contents have been placed into this stream. (If a mapped stream is null an empty stream is used, instead.)

This is an intermediate operation.

Parameters

mapper:LongFunction<? extends LongStream>: a non-interfering, stateless function to apply to each element which produces a LongStream of new values

Returns:LongStream

the new stream

See Also

Stream#flatMap(Function)

forEach	back to summary
public void forEach(LongConsumer action) Performs an action for each element of this stream. This is a terminal operation. For parallel stream pipelines, this operation does not guarantee to respect the encounter order of the stream, as doing so would sacrifice the benefit of parallelism. For any given element, the action may be performed at whatever time and in whatever thread the library chooses. If the action accesses shared state, it is responsible for providing the required synchronization. Parameters action:LongConsumer a non-interfering action to perform on the elements

forEach

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public void forEach(LongConsumer action)

Performs an action for each element of this stream.

This is a terminal operation.

For parallel stream pipelines, this operation does not guarantee to respect the encounter order of the stream, as doing so would sacrifice the benefit of parallelism. For any given element, the action may be performed at whatever time and in whatever thread the library chooses. If the action accesses shared state, it is responsible for providing the required synchronization.

Parameters

action:LongConsumer: a non-interfering action to perform on the elements

forEachOrdered back to summary

forEachOrdered	back to summary
public void forEachOrdered(LongConsumer action) Performs an action for each element of this stream, guaranteeing that each element is processed in encounter order for streams that have a defined encounter order. This is a terminal operation. Parameters action:LongConsumer a non-interfering action to perform on the elements See Also `forEach(LongConsumer)`

public void forEachOrdered(LongConsumer action)

Performs an action for each element of this stream, guaranteeing that each element is processed in encounter order for streams that have a defined encounter order.

This is a terminal operation.

Parameters

action:LongConsumer: a non-interfering action to perform on the elements

See Also

forEach(LongConsumer)

generate back to summary

generate	back to summary
public static LongStream generate(LongSupplier s) Returns an infinite sequential unordered stream where each element is generated by the provided `LongSupplier`. This is suitable for generating constant streams, streams of random elements, etc. Parameters s:LongSupplier the `LongSupplier` for generated elements Returns:LongStream a new infinite sequential unordered `LongStream`

public static LongStream generate(LongSupplier s)

Returns an infinite sequential unordered stream where each element is generated by the provided LongSupplier. This is suitable for generating constant streams, streams of random elements, etc.

Parameters

s:LongSupplier: the LongSupplier for generated elements

Returns:LongStream

a new infinite sequential unordered LongStream

iterate back to summary

iterate	back to summary
public static LongStream iterate(final long seed, final LongUnaryOperator f) Returns an infinite sequential ordered `LongStream` produced by iterative application of a function `f` to an initial element `seed`, producing a `Stream` consisting of `seed`, `f(seed)`, `f(f(seed))`, etc. The first element (position `0`) in the `LongStream` will be the provided `seed`. For `n > 0`, the element at position `n`, will be the result of applying the function `f` to the element at position `n - 1`. The action of applying `f` for one element happens-before the action of applying `f` for subsequent elements. For any given element the action may be performed in whatever thread the library chooses. Parameters seed:long the initial element f:LongUnaryOperator a function to be applied to the previous element to produce a new element Returns:LongStream a new sequential `LongStream`

public static LongStream iterate(final long seed, final LongUnaryOperator f)

Returns an infinite sequential ordered LongStream produced by iterative application of a function f to an initial element seed, producing a Stream consisting of seed, f(seed), f(f(seed)), etc.

The first element (position 0) in the LongStream will be the provided seed. For n > 0, the element at position n, will be the result of applying the function f to the element at position n - 1.

The action of applying f for one element happens-before the action of applying f for subsequent elements. For any given element the action may be performed in whatever thread the library chooses.

Parameters

seed:long: the initial element
f:LongUnaryOperator: a function to be applied to the previous element to produce a new element

Returns:LongStream

a new sequential LongStream

iterate back to summary

iterate	back to summary
public static LongStream iterate(long seed, LongPredicate hasNext, LongUnaryOperator next) Returns a sequential ordered `LongStream` produced by iterative application of the given `next` function to an initial element, conditioned on satisfying the given `hasNext` predicate. The stream terminates as soon as the `hasNext` predicate returns false. `LongStream.iterate` should produce the same sequence of elements as produced by the corresponding for-loop: `for (long index=seed; hasNext.test(index); index = next.applyAsLong(index)) { ... }` The resulting sequence may be empty if the `hasNext` predicate does not hold on the seed value. Otherwise the first element will be the supplied `seed` value, the next element (if present) will be the result of applying the `next` function to the `seed` value, and so on iteratively until the `hasNext` predicate indicates that the stream should terminate. The action of applying the `hasNext` predicate to an element happens-before the action of applying the `next` function to that element. The action of applying the `next` function for one element happens-before the action of applying the `hasNext` predicate for subsequent elements. For any given element an action may be performed in whatever thread the library chooses. Parameters seed:long the initial element hasNext:LongPredicate a predicate to apply to elements to determine when the stream must terminate. next:LongUnaryOperator a function to be applied to the previous element to produce a new element Returns:LongStream a new sequential `LongStream` Since 9

public static LongStream iterate(long seed, LongPredicate hasNext, LongUnaryOperator next)

Returns a sequential ordered LongStream produced by iterative application of the given next function to an initial element, conditioned on satisfying the given hasNext predicate. The stream terminates as soon as the hasNext predicate returns false.

LongStream.iterate should produce the same sequence of elements as produced by the corresponding for-loop:

for (long index=seed; hasNext.test(index); index = next.applyAsLong(index)) {
        ...
    }

The resulting sequence may be empty if the hasNext predicate does not hold on the seed value. Otherwise the first element will be the supplied seed value, the next element (if present) will be the result of applying the next function to the seed value, and so on iteratively until the hasNext predicate indicates that the stream should terminate.

The action of applying the hasNext predicate to an element happens-before the action of applying the next function to that element. The action of applying the next function for one element happens-before the action of applying the hasNext predicate for subsequent elements. For any given element an action may be performed in whatever thread the library chooses.

Parameters

seed:long: the initial element
hasNext:LongPredicate: a predicate to apply to elements to determine when the stream must terminate.
next:LongUnaryOperator: a function to be applied to the previous element to produce a new element

Returns:LongStream

a new sequential LongStream

Since

iterator	back to summary
public PrimitiveIterator.OfLong iterator() Redeclares java.util.stream.BaseStream.iterator. Doc from java.util.stream.BaseStream.iterator. Returns an iterator for the elements of this stream. This is a terminal operation. Returns:PrimitiveIterator.OfLong the element iterator for this stream Annotations @Override

iterator

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public PrimitiveIterator.OfLong iterator()

Redeclares java.util.stream.BaseStream.iterator.

Doc from java.util.stream.BaseStream.iterator.

Returns an iterator for the elements of this stream.

This is a terminal operation.

Returns:PrimitiveIterator.OfLong

the element iterator for this stream

Annotations

@Override

limit back to summary

limit	back to summary
public LongStream limit(long maxSize) Returns a stream consisting of the elements of this stream, truncated to be no longer than `maxSize` in length. This is a short-circuiting stateful intermediate operation. API Note While `limit()` is generally a cheap operation on sequential stream pipelines, it can be quite expensive on ordered parallel pipelines, especially for large values of `maxSize`, since `limit(n)` is constrained to return not just any n elements, but the first n elements in the encounter order. Using an unordered stream source (such as `generate(LongSupplier)`) or removing the ordering constraint with `unordered()` may result in significant speedups of `limit()` in parallel pipelines, if the semantics of your situation permit. If consistency with encounter order is required, and you are experiencing poor performance or memory utilization with `limit()` in parallel pipelines, switching to sequential execution with `sequential()` may improve performance. Parameters maxSize:long the number of elements the stream should be limited to Returns:LongStream the new stream Exceptions IllegalArgumentException: if `maxSize` is negative

public LongStream limit(long maxSize)

Returns a stream consisting of the elements of this stream, truncated to be no longer than maxSize in length.

This is a short-circuiting stateful intermediate operation.

API Note

While limit() is generally a cheap operation on sequential stream pipelines, it can be quite expensive on ordered parallel pipelines, especially for large values of maxSize, since limit(n) is constrained to return not just any n elements, but the first n elements in the encounter order. Using an unordered stream source (such as generate(LongSupplier)) or removing the ordering constraint with unordered() may result in significant speedups of limit() in parallel pipelines, if the semantics of your situation permit. If consistency with encounter order is required, and you are experiencing poor performance or memory utilization with limit() in parallel pipelines, switching to sequential execution with sequential() may improve performance.

Parameters

maxSize:long: the number of elements the stream should be limited to

Returns:LongStream

the new stream

Exceptions

IllegalArgumentException:: if maxSize is negative

map	back to summary
public LongStream map(LongUnaryOperator mapper) Returns a stream consisting of the results of applying the given function to the elements of this stream. This is an intermediate operation. Parameters mapper:LongUnaryOperator a non-interfering, stateless function to apply to each element Returns:LongStream the new stream

map

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public LongStream map(LongUnaryOperator mapper)

Returns a stream consisting of the results of applying the given function to the elements of this stream.

This is an intermediate operation.

Parameters

mapper:LongUnaryOperator: a non-interfering, stateless function to apply to each element

Returns:LongStream

the new stream

mapMulti back to summary

mapMulti	back to summary
public default LongStream mapMulti(LongStream.LongMapMultiConsumer mapper) Returns a stream consisting of the results of replacing each element of this stream with multiple elements, specifically zero or more elements. Replacement is performed by applying the provided mapping function to each element in conjunction with a consumer argument that accepts replacement elements. The mapping function calls the consumer zero or more times to provide the replacement elements. This is an intermediate operation. If the consumer argument is used outside the scope of its application to the mapping function, the results are undefined. Implementation Specification The default implementation invokes `flatMap` on this stream, passing a function that behaves as follows. First, it calls the mapper function with a `LongConsumer` that accumulates replacement elements into a newly created internal buffer. When the mapper function returns, it creates a `LongStream` from the internal buffer. Finally, it returns this stream to `flatMap`. Parameters mapper:LongStream.LongMapMultiConsumer a non-interfering, stateless function that generates replacement elements Returns:LongStream the new stream Since 16 See Also `Stream.mapMulti`

public default LongStream mapMulti(LongStream.LongMapMultiConsumer mapper)

Returns a stream consisting of the results of replacing each element of this stream with multiple elements, specifically zero or more elements. Replacement is performed by applying the provided mapping function to each element in conjunction with a consumer argument that accepts replacement elements. The mapping function calls the consumer zero or more times to provide the replacement elements.

This is an intermediate operation.

If the consumer argument is used outside the scope of its application to the mapping function, the results are undefined.

Implementation Specification

The default implementation invokes flatMap on this stream, passing a function that behaves as follows. First, it calls the mapper function with a LongConsumer that accumulates replacement elements into a newly created internal buffer. When the mapper function returns, it creates a LongStream from the internal buffer. Finally, it returns this stream to flatMap.

Parameters

mapper:LongStream.LongMapMultiConsumer: a non-interfering, stateless function that generates replacement elements

Returns:LongStream

the new stream

Since

See Also

Stream.mapMulti

mapToDouble back to summary

mapToDouble	back to summary
public DoubleStream mapToDouble(LongToDoubleFunction mapper) Returns a `DoubleStream` consisting of the results of applying the given function to the elements of this stream. This is an intermediate operation. Parameters mapper:LongToDoubleFunction a non-interfering, stateless function to apply to each element Returns:DoubleStream the new stream

public DoubleStream mapToDouble(LongToDoubleFunction mapper)

Returns a DoubleStream consisting of the results of applying the given function to the elements of this stream.

This is an intermediate operation.

Parameters

mapper:LongToDoubleFunction: a non-interfering, stateless function to apply to each element

Returns:DoubleStream

the new stream

mapToInt back to summary

mapToInt	back to summary
public IntStream mapToInt(LongToIntFunction mapper) Returns an `IntStream` consisting of the results of applying the given function to the elements of this stream. This is an intermediate operation. Parameters mapper:LongToIntFunction a non-interfering, stateless function to apply to each element Returns:IntStream the new stream

public IntStream mapToInt(LongToIntFunction mapper)

Returns an IntStream consisting of the results of applying the given function to the elements of this stream.

This is an intermediate operation.

Parameters

mapper:LongToIntFunction: a non-interfering, stateless function to apply to each element

Returns:IntStream

the new stream

mapToObj back to summary

mapToObj	back to summary
public <U> Stream<U> mapToObj(LongFunction<? extends U> mapper) Returns an object-valued `Stream` consisting of the results of applying the given function to the elements of this stream. This is an intermediate operation. Parameters <U> the element type of the new stream mapper:LongFunction<? extends U> a non-interfering, stateless function to apply to each element Returns:Stream<U> the new stream

public <U> Stream<U> mapToObj(LongFunction<? extends U> mapper)

Returns an object-valued Stream consisting of the results of applying the given function to the elements of this stream.

This is an intermediate operation.

Parameters

<U>: the element type of the new stream
mapper:LongFunction<? extends U>: a non-interfering, stateless function to apply to each element

Returns:Stream<U>

the new stream

max back to summary

max	back to summary
public OptionalLong max() Returns an `OptionalLong` describing the maximum element of this stream, or an empty optional if this stream is empty. This is a special case of a reduction and is equivalent to: `return reduce(Long::max);` This is a terminal operation. Returns:OptionalLong an `OptionalLong` containing the maximum element of this stream, or an empty `OptionalLong` if the stream is empty

public OptionalLong max()

Returns an OptionalLong describing the maximum element of this stream, or an empty optional if this stream is empty. This is a special case of a reduction and is equivalent to:

return reduce(Long::max);

This is a terminal operation.

Returns:OptionalLong: an OptionalLong containing the maximum element of this stream, or an empty OptionalLong if the stream is empty

min back to summary

min	back to summary
public OptionalLong min() Returns an `OptionalLong` describing the minimum element of this stream, or an empty optional if this stream is empty. This is a special case of a reduction and is equivalent to: `return reduce(Long::min);` This is a terminal operation. Returns:OptionalLong an `OptionalLong` containing the minimum element of this stream, or an empty `OptionalLong` if the stream is empty

public OptionalLong min()

Returns an OptionalLong describing the minimum element of this stream, or an empty optional if this stream is empty. This is a special case of a reduction and is equivalent to:

return reduce(Long::min);

This is a terminal operation.

Returns:OptionalLong: an OptionalLong containing the minimum element of this stream, or an empty OptionalLong if the stream is empty

noneMatch back to summary

noneMatch	back to summary
public boolean noneMatch(LongPredicate predicate) Returns whether no elements of this stream match the provided predicate. May not evaluate the predicate on all elements if not necessary for determining the result. If the stream is empty then `true` is returned and the predicate is not evaluated. This is a short-circuiting terminal operation. API Note This method evaluates the universal quantification of the negated predicate over the elements of the stream (for all x ~P(x)). If the stream is empty, the quantification is said to be vacuously satisfied and is always `true`, regardless of P(x). Parameters predicate:LongPredicate a non-interfering, stateless predicate to apply to elements of this stream Returns:boolean `true` if either no elements of the stream match the provided predicate or the stream is empty, otherwise `false`

public boolean noneMatch(LongPredicate predicate)

Returns whether no elements of this stream match the provided predicate. May not evaluate the predicate on all elements if not necessary for determining the result. If the stream is empty then true is returned and the predicate is not evaluated.

This is a short-circuiting terminal operation.

API Note

This method evaluates the universal quantification of the negated predicate over the elements of the stream (for all x ~P(x)). If the stream is empty, the quantification is said to be vacuously satisfied and is always true, regardless of P(x).

Parameters

predicate:LongPredicate: a non-interfering, stateless predicate to apply to elements of this stream

Returns:boolean

true if either no elements of the stream match the provided predicate or the stream is empty, otherwise false

of back to summary

of	back to summary
public static LongStream of(long t) Returns a sequential `LongStream` containing a single element. Parameters t:long the single element Returns:LongStream a singleton sequential stream

public static LongStream of(long t)

Returns a sequential LongStream containing a single element.

Parameters

t:long: the single element

Returns:LongStream

a singleton sequential stream

of	back to summary
public static LongStream of(long... values) Returns a sequential ordered stream whose elements are the specified values. Parameters values:long[] the elements of the new stream Returns:LongStream the new stream

back to summary

public static LongStream of(long... values)

Returns a sequential ordered stream whose elements are the specified values.

Parameters

values:long[]: the elements of the new stream

Returns:LongStream

the new stream

parallel	back to summary
public LongStream parallel() Redeclares java.util.stream.BaseStream.parallel. Doc from java.util.stream.BaseStream.parallel. Returns an equivalent stream that is parallel. May return itself, either because the stream was already parallel, or because the underlying stream state was modified to be parallel. This is an intermediate operation. Returns:LongStream a parallel stream Annotations @Override

parallel

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public LongStream parallel()

Redeclares java.util.stream.BaseStream.parallel.

Doc from java.util.stream.BaseStream.parallel.

Returns an equivalent stream that is parallel. May return itself, either because the stream was already parallel, or because the underlying stream state was modified to be parallel.

This is an intermediate operation.

Returns:LongStream

a parallel stream

Annotations

@Override

peek back to summary

peek	back to summary
public LongStream peek(LongConsumer action) Returns a stream consisting of the elements of this stream, additionally performing the provided action on each element as elements are consumed from the resulting stream. This is an intermediate operation. For parallel stream pipelines, the action may be called at whatever time and in whatever thread the element is made available by the upstream operation. If the action modifies shared state, it is responsible for providing the required synchronization. API Note This method exists mainly to support debugging, where you want to see the elements as they flow past a certain point in a pipeline: `LongStream.of(1, 2, 3, 4) .filter(e -> e > 2) .peek(e -> System.out.println("Filtered value: " + e)) .map(e -> e * e) .peek(e -> System.out.println("Mapped value: " + e)) .sum();` In cases where the stream implementation is able to optimize away the production of some or all the elements (such as with short-circuiting operations like `findFirst`, or in the example described in `count`), the action will not be invoked for those elements. Parameters action:LongConsumer a non-interfering action to perform on the elements as they are consumed from the stream Returns:LongStream the new stream

public LongStream peek(LongConsumer action)

Returns a stream consisting of the elements of this stream, additionally performing the provided action on each element as elements are consumed from the resulting stream.

This is an intermediate operation.

For parallel stream pipelines, the action may be called at whatever time and in whatever thread the element is made available by the upstream operation. If the action modifies shared state, it is responsible for providing the required synchronization.

API Note

This method exists mainly to support debugging, where you want to see the elements as they flow past a certain point in a pipeline:

LongStream.of(1, 2, 3, 4)
        .filter(e -> e > 2)
        .peek(e -> System.out.println("Filtered value: " + e))
        .map(e -> e * e)
        .peek(e -> System.out.println("Mapped value: " + e))
        .sum();

In cases where the stream implementation is able to optimize away the production of some or all the elements (such as with short-circuiting operations like findFirst, or in the example described in count), the action will not be invoked for those elements.

Parameters

action:LongConsumer: a non-interfering action to perform on the elements as they are consumed from the stream

Returns:LongStream

the new stream

range back to summary

range	back to summary
public static LongStream range(long startInclusive, final long endExclusive) Returns a sequential ordered `LongStream` from `startInclusive` (inclusive) to `endExclusive` (exclusive) by an incremental step of `1`. API Note An equivalent sequence of increasing values can be produced sequentially using a `for` loop as follows: `for (long i = startInclusive; i < endExclusive ; i++) { ... }` Parameters startInclusive:long the (inclusive) initial value endExclusive:long the exclusive upper bound Returns:LongStream a sequential `LongStream` for the range of `long` elements

public static LongStream range(long startInclusive, final long endExclusive)

Returns a sequential ordered LongStream from startInclusive (inclusive) to endExclusive (exclusive) by an incremental step of 1.

API Note

An equivalent sequence of increasing values can be produced sequentially using a for loop as follows:

for (long i = startInclusive; i < endExclusive ; i++) { ... }

Parameters

startInclusive:long: the (inclusive) initial value
endExclusive:long: the exclusive upper bound

Returns:LongStream

a sequential LongStream for the range of long elements

rangeClosed back to summary

rangeClosed	back to summary
public static LongStream rangeClosed(long startInclusive, final long endInclusive) Returns a sequential ordered `LongStream` from `startInclusive` (inclusive) to `endInclusive` (inclusive) by an incremental step of `1`. API Note An equivalent sequence of increasing values can be produced sequentially using a `for` loop as follows: `for (long i = startInclusive; i <= endInclusive ; i++) { ... }` Parameters startInclusive:long the (inclusive) initial value endInclusive:long the inclusive upper bound Returns:LongStream a sequential `LongStream` for the range of `long` elements

public static LongStream rangeClosed(long startInclusive, final long endInclusive)

Returns a sequential ordered LongStream from startInclusive (inclusive) to endInclusive (inclusive) by an incremental step of 1.

API Note

An equivalent sequence of increasing values can be produced sequentially using a for loop as follows:

for (long i = startInclusive; i <= endInclusive ; i++) { ... }

Parameters

startInclusive:long: the (inclusive) initial value
endInclusive:long: the inclusive upper bound

Returns:LongStream

a sequential LongStream for the range of long elements

reduce back to summary

reduce	back to summary
public long reduce(long identity, LongBinaryOperator op) Performs a reduction on the elements of this stream, using the provided identity value and an associative accumulation function, and returns the reduced value. This is equivalent to: `long result = identity; for (long element : this stream) result = accumulator.applyAsLong(result, element) return result;` but is not constrained to execute sequentially. The `identity` value must be an identity for the accumulator function. This means that for all `x`, `accumulator.apply(identity, x)` is equal to `x`. The `accumulator` function must be an associative function. This is a terminal operation. API Note Sum, min, max, and average are all special cases of reduction. Summing a stream of numbers can be expressed as: `long sum = integers.reduce(0, (a, b) -> a+b);` or more compactly: `long sum = integers.reduce(0, Long::sum);` While this may seem a more roundabout way to perform an aggregation compared to simply mutating a running total in a loop, reduction operations parallelize more gracefully, without needing additional synchronization and with greatly reduced risk of data races. Parameters identity:long the identity value for the accumulating function op:LongBinaryOperator an associative, non-interfering, stateless function for combining two values Returns:long the result of the reduction See Also `sum()`, `min()`, `max()`, `average()`

public long reduce(long identity, LongBinaryOperator op)

Performs a reduction on the elements of this stream, using the provided identity value and an associative accumulation function, and returns the reduced value. This is equivalent to:

long result = identity;
    for (long element : this stream)
        result = accumulator.applyAsLong(result, element)
    return result;

but is not constrained to execute sequentially.

The identity value must be an identity for the accumulator function. This means that for all x, accumulator.apply(identity, x) is equal to x. The accumulator function must be an associative function.

This is a terminal operation.

API Note

Sum, min, max, and average are all special cases of reduction. Summing a stream of numbers can be expressed as:

long sum = integers.reduce(0, (a, b) -> a+b);

or more compactly:

long sum = integers.reduce(0, Long::sum);

While this may seem a more roundabout way to perform an aggregation compared to simply mutating a running total in a loop, reduction operations parallelize more gracefully, without needing additional synchronization and with greatly reduced risk of data races.

Parameters

identity:long: the identity value for the accumulating function
op:LongBinaryOperator: an associative, non-interfering, stateless function for combining two values

Returns:long

the result of the reduction

See Also

sum(), min(), max(), average()

reduce back to summary

reduce	back to summary
public OptionalLong reduce(LongBinaryOperator op) Performs a reduction on the elements of this stream, using an associative accumulation function, and returns an `OptionalLong` describing the reduced value, if any. This is equivalent to: `boolean foundAny = false; long result = null; for (long element : this stream) { if (!foundAny) { foundAny = true; result = element; } else result = accumulator.applyAsLong(result, element); } return foundAny ? OptionalLong.of(result) : OptionalLong.empty();` but is not constrained to execute sequentially. The `accumulator` function must be an associative function. This is a terminal operation. Parameters op:LongBinaryOperator an associative, non-interfering, stateless function for combining two values Returns:OptionalLong the result of the reduction See Also `reduce(long, LongBinaryOperator)`

public OptionalLong reduce(LongBinaryOperator op)

Performs a reduction on the elements of this stream, using an associative accumulation function, and returns an OptionalLong describing the reduced value, if any. This is equivalent to:

boolean foundAny = false;
    long result = null;
    for (long element : this stream) {
        if (!foundAny) {
            foundAny = true;
            result = element;
        }
        else
            result = accumulator.applyAsLong(result, element);
    }
    return foundAny ? OptionalLong.of(result) : OptionalLong.empty();

but is not constrained to execute sequentially.

The accumulator function must be an associative function.

This is a terminal operation.

Parameters

op:LongBinaryOperator: an associative, non-interfering, stateless function for combining two values

Returns:OptionalLong

the result of the reduction

See Also

reduce(long, LongBinaryOperator)

sequential	back to summary
public LongStream sequential() Redeclares java.util.stream.BaseStream.sequential. Doc from java.util.stream.BaseStream.sequential. Returns an equivalent stream that is sequential. May return itself, either because the stream was already sequential, or because the underlying stream state was modified to be sequential. This is an intermediate operation. Returns:LongStream a sequential stream Annotations @Override

sequential

back to summary

public LongStream sequential()

Redeclares java.util.stream.BaseStream.sequential.

Doc from java.util.stream.BaseStream.sequential.

Returns an equivalent stream that is sequential. May return itself, either because the stream was already sequential, or because the underlying stream state was modified to be sequential.

This is an intermediate operation.

Returns:LongStream

a sequential stream

Annotations

@Override

skip back to summary

skip	back to summary
public LongStream skip(long n) Returns a stream consisting of the remaining elements of this stream after discarding the first `n` elements of the stream. If this stream contains fewer than `n` elements then an empty stream will be returned. This is a stateful intermediate operation. API Note While `skip()` is generally a cheap operation on sequential stream pipelines, it can be quite expensive on ordered parallel pipelines, especially for large values of `n`, since `skip(n)` is constrained to skip not just any n elements, but the first n elements in the encounter order. Using an unordered stream source (such as `generate(LongSupplier)`) or removing the ordering constraint with `unordered()` may result in significant speedups of `skip()` in parallel pipelines, if the semantics of your situation permit. If consistency with encounter order is required, and you are experiencing poor performance or memory utilization with `skip()` in parallel pipelines, switching to sequential execution with `sequential()` may improve performance. Parameters n:long the number of leading elements to skip Returns:LongStream the new stream Exceptions IllegalArgumentException: if `n` is negative

public LongStream skip(long n)

Returns a stream consisting of the remaining elements of this stream after discarding the first n elements of the stream. If this stream contains fewer than n elements then an empty stream will be returned.

This is a stateful intermediate operation.

API Note

While skip() is generally a cheap operation on sequential stream pipelines, it can be quite expensive on ordered parallel pipelines, especially for large values of n, since skip(n) is constrained to skip not just any n elements, but the first n elements in the encounter order. Using an unordered stream source (such as generate(LongSupplier)) or removing the ordering constraint with unordered() may result in significant speedups of skip() in parallel pipelines, if the semantics of your situation permit. If consistency with encounter order is required, and you are experiencing poor performance or memory utilization with skip() in parallel pipelines, switching to sequential execution with sequential() may improve performance.

Parameters

n:long: the number of leading elements to skip

Returns:LongStream

the new stream

Exceptions

IllegalArgumentException:: if n is negative

sorted	back to summary
public LongStream sorted() Returns a stream consisting of the elements of this stream in sorted order. This is a stateful intermediate operation. Returns:LongStream the new stream

sorted

back to summary

public LongStream sorted()

Returns a stream consisting of the elements of this stream in sorted order.

This is a stateful intermediate operation.

Returns:LongStream: the new stream

spliterator	back to summary
public Spliterator.OfLong spliterator() Redeclares java.util.stream.BaseStream.spliterator. Doc from java.util.stream.BaseStream.spliterator. Returns a spliterator for the elements of this stream. This is a terminal operation. Returns:Spliterator.OfLong the element spliterator for this stream Annotations @Override

spliterator

back to summary

public Spliterator.OfLong spliterator()

Redeclares java.util.stream.BaseStream.spliterator.

Doc from java.util.stream.BaseStream.spliterator.

Returns a spliterator for the elements of this stream.

This is a terminal operation.

Returns:Spliterator.OfLong

the element spliterator for this stream

Annotations

@Override

sum back to summary

sum	back to summary
public long sum() Returns the sum of elements in this stream. This is a special case of a reduction and is equivalent to: `return reduce(0, Long::sum);` This is a terminal operation. Returns:long the sum of elements in this stream

public long sum()

Returns the sum of elements in this stream. This is a special case of a reduction and is equivalent to:

return reduce(0, Long::sum);

This is a terminal operation.

Returns:long: the sum of elements in this stream

summaryStatistics back to summary

summaryStatistics	back to summary
public LongSummaryStatistics summaryStatistics() Returns a `LongSummaryStatistics` describing various summary data about the elements of this stream. This is a special case of a reduction. This is a terminal operation. Returns:LongSummaryStatistics a `LongSummaryStatistics` describing various summary data about the elements of this stream

public LongSummaryStatistics summaryStatistics()

Returns a LongSummaryStatistics describing various summary data about the elements of this stream. This is a special case of a reduction.

This is a terminal operation.

Returns:LongSummaryStatistics: a LongSummaryStatistics describing various summary data about the elements of this stream

takeWhile back to summary

takeWhile	back to summary
public default LongStream takeWhile(LongPredicate predicate) Returns, if this stream is ordered, a stream consisting of the longest prefix of elements taken from this stream that match the given predicate. Otherwise returns, if this stream is unordered, a stream consisting of a subset of elements taken from this stream that match the given predicate. If this stream is ordered then the longest prefix is a contiguous sequence of elements of this stream that match the given predicate. The first element of the sequence is the first element of this stream, and the element immediately following the last element of the sequence does not match the given predicate. If this stream is unordered, and some (but not all) elements of this stream match the given predicate, then the behavior of this operation is nondeterministic; it is free to take any subset of matching elements (which includes the empty set). Independent of whether this stream is ordered or unordered if all elements of this stream match the given predicate then this operation takes all elements (the result is the same as the input), or if no elements of the stream match the given predicate then no elements are taken (the result is an empty stream). This is a short-circuiting stateful intermediate operation. Implementation Specification The default implementation obtains the `spliterator` of this stream, wraps that spliterator so as to support the semantics of this operation on traversal, and returns a new stream associated with the wrapped spliterator. The returned stream preserves the execution characteristics of this stream (namely parallel or sequential execution as per `isParallel()`) but the wrapped spliterator may choose to not support splitting. When the returned stream is closed, the close handlers for both the returned and this stream are invoked. API Note While `takeWhile()` is generally a cheap operation on sequential stream pipelines, it can be quite expensive on ordered parallel pipelines, since the operation is constrained to return not just any valid prefix, but the longest prefix of elements in the encounter order. Using an unordered stream source (such as `generate(LongSupplier)`) or removing the ordering constraint with `unordered()` may result in significant speedups of `takeWhile()` in parallel pipelines, if the semantics of your situation permit. If consistency with encounter order is required, and you are experiencing poor performance or memory utilization with `takeWhile()` in parallel pipelines, switching to sequential execution with `sequential()` may improve performance. Parameters predicate:LongPredicate a non-interfering, stateless predicate to apply to elements to determine the longest prefix of elements. Returns:LongStream the new stream Since 9

public default LongStream takeWhile(LongPredicate predicate)

Returns, if this stream is ordered, a stream consisting of the longest prefix of elements taken from this stream that match the given predicate. Otherwise returns, if this stream is unordered, a stream consisting of a subset of elements taken from this stream that match the given predicate.

If this stream is unordered, and some (but not all) elements of this stream match the given predicate, then the behavior of this operation is nondeterministic; it is free to take any subset of matching elements (which includes the empty set).

Independent of whether this stream is ordered or unordered if all elements of this stream match the given predicate then this operation takes all elements (the result is the same as the input), or if no elements of the stream match the given predicate then no elements are taken (the result is an empty stream).

This is a short-circuiting stateful intermediate operation.

Implementation Specification

API Note

While takeWhile() is generally a cheap operation on sequential stream pipelines, it can be quite expensive on ordered parallel pipelines, since the operation is constrained to return not just any valid prefix, but the longest prefix of elements in the encounter order. Using an unordered stream source (such as generate(LongSupplier)) or removing the ordering constraint with unordered() may result in significant speedups of takeWhile() in parallel pipelines, if the semantics of your situation permit. If consistency with encounter order is required, and you are experiencing poor performance or memory utilization with takeWhile() in parallel pipelines, switching to sequential execution with sequential() may improve performance.

Parameters

predicate:LongPredicate: a non-interfering, stateless predicate to apply to elements to determine the longest prefix of elements.

Returns:LongStream

the new stream

Since

toArray	back to summary
public long[] toArray() Returns an array containing the elements of this stream. This is a terminal operation. Returns:long[] an array containing the elements of this stream

toArray

back to summary

public long[] toArray()

Returns an array containing the elements of this stream.

This is a terminal operation.

Returns:long[]: an array containing the elements of this stream

public Interface LongStream

Nested and Inner Type Summary

Method Summary

Method Detail

public Interface LongStream.Builder

Method Summary

Method Detail

public Interface LongStream.LongMapMultiConsumer

Method Summary

Method Detail

Modifier and Type	Method and Description
public void	accept(long the input argument t) Redeclares java.util.function.LongConsumer.accept. Adds an element to the stream being built.
public default LongStream.Builder	Returns: `this` builder add(long the element to add t) Adds an element to the stream being built.
public LongStream	Returns: the built stream build() Builds the stream, transitioning this builder to the built state.