IntStream

interface IntStream : BaseStream<Int!, IntStream!>
java.util.stream.IntStream

A sequence of primitive int-valued elements supporting sequential and parallel aggregate operations. This is the int primitive specialization of .

The following example illustrates an aggregate operation using Stream and IntStream, computing the sum of the weights of the red widgets:

int sum = widgets.stream() .filter(w -> w.getColor() == RED) .mapToInt(w -> w.getWeight()) .sum(); 
See the class documentation for Stream and the package documentation for java.util.stream for additional specification of streams, stream operations, stream pipelines, and parallelism.
Requires API level 24 (Android 7.0, Nougat)

Summary

Nested classes
abstract

A mutable builder for an IntStream.

Public methods
abstract LongStream!

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

abstract R
collect(supplier: Supplier<R>!, accumulator: ObjIntConsumer<R>!, combiner: BiConsumer<R, R>!)

Performs a mutable reduction operation on the elements of this stream.

abstract Stream<U>!
mapToObj(mapper: IntFunction<out U>!)

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

abstract Int
reduce(identity: Int, op: IntBinaryOperator!)

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

abstract OptionalInt!

Performs a reduction on the elements of this stream, using an associative accumulation function, and returns an OptionalInt describing the reduced value, if any.

abstract IntStream!

Returns an equivalent stream that is sequential.

abstract Long

Returns the count of elements in this stream.

abstract Boolean
anyMatch(predicate: IntPredicate!)

Returns whether any elements of this stream match the provided predicate.

abstract OptionalInt!

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

abstract PrimitiveIterator.OfInt!

Returns an iterator for the elements of this stream.

abstract IntStream!

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

abstract IntStream!
filter(predicate: IntPredicate!)

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

abstract IntSummaryStatistics!

Returns an IntSummaryStatistics describing various summary data about the elements of this stream.

abstract Stream<Int!>!

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

abstract IntStream!
flatMap(mapper: IntFunction<out IntStream!>!)

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.

abstract Unit
forEach(action: IntConsumer!)

Performs an action for each element of this stream.

abstract IntStream!
peek(action: IntConsumer!)

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.

abstract Boolean
allMatch(predicate: IntPredicate!)

Returns whether all elements of this stream match the provided predicate.

abstract OptionalInt!

Returns an OptionalInt describing the first element of this stream, or an empty OptionalInt if the stream is empty.

abstract OptionalInt!
min()

Returns an OptionalInt describing the minimum element of this stream, or an empty optional if this stream is empty.

abstract Spliterator.OfInt!

Returns a spliterator for the elements of this stream.

abstract IntArray!

Returns an array containing the elements of this stream.

abstract DoubleStream!

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

abstract IntStream!
limit(maxSize: Long)

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

abstract Int
sum()

Returns the sum of elements in this stream.

abstract Unit

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.

abstract IntStream!
skip(n: Long)

Returns a stream consisting of the remaining elements of this stream after discarding the first n elements of the stream.

abstract IntStream!

Returns an equivalent stream that is parallel.

abstract DoubleStream!

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

abstract OptionalInt!
max()

Returns an OptionalInt describing the maximum element of this stream, or an empty optional if this stream is empty.

abstract LongStream!

Returns a LongStream consisting of the elements of this stream, converted to long.

abstract IntStream!

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

abstract Boolean
noneMatch(predicate: IntPredicate!)

Returns whether no elements of this stream match the provided predicate.

abstract IntStream!

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

abstract OptionalDouble!

Returns an OptionalDouble describing the arithmetic mean of elements of this stream, or an empty optional if this stream is empty.

open static IntStream.Builder!

Returns a builder for an IntStream.

open static IntStream!

Returns an empty sequential IntStream.

open static IntStream!
of(t: Int)

Returns a sequential IntStream containing a single element.

open static IntStream!
of(vararg values: Int)

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

open static IntStream!

Returns an infinite sequential ordered IntStream 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.

open static IntStream!

Returns an infinite sequential unordered stream where each element is generated by the provided IntSupplier.

open static IntStream!
range(startInclusive: Int, endExclusive: Int)

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

open static IntStream!
rangeClosed(startInclusive: Int, endInclusive: Int)

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

open static IntStream!

Creates a lazily concatenated stream whose elements are all the elements of the first stream followed by all the elements of the second stream.

Inherited functions

Public methods

mapToLong

added in API level 24
abstract fun mapToLong(mapper: IntToLongFunction!): LongStream!

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

This is an intermediate operation.
Requires API level 24 (Android 7.0, Nougat)

Parameters
mapper IntToLongFunction!: a non-interfering, stateless function to apply to each element
Return
LongStream!: the new stream

collect

added in API level 24
abstract fun <R : Any!> collect(supplier: Supplier<R>!, accumulator: ObjIntConsumer<R>!, combiner: BiConsumer<R, R>!): R

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 (int element : this stream) accumulator.accept(result, element); return result; 

Like #reduce(int, IntBinaryOperator), collect operations can be parallelized without requiring additional synchronization.

This is a terminal operation.
Requires API level 24 (Android 7.0, Nougat)

Parameters
<R> Supplier<R>!: type of the result
supplier Supplier<R>!: a function that creates a new result container. For a parallel execution, this function may be called multiple times and must return a fresh value each time.
accumulator Supplier<R>!: an associative, non-interfering, stateless function for incorporating an additional element into a result
combiner Supplier<R>!: an associative, non-interfering, stateless function for combining two values, which must be compatible with the accumulator function
Return
R: the result of the reduction

mapToObj

added in API level 24
abstract fun <U : Any!> mapToObj(mapper: IntFunction<out U>!): Stream<U>!

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.
Requires API level 24 (Android 7.0, Nougat)

Parameters
<U> IntFunction<out U>!: the element type of the new stream
mapper IntFunction<out U>!: a non-interfering, stateless function to apply to each element
Return
Stream<U>!: the new stream

reduce

added in API level 24
abstract fun reduce(identity: Int, op: IntBinaryOperator!): Int

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:

int result = identity; for (int element : this stream) result = accumulator.applyAsInt(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.
Requires API level 24 (Android 7.0, Nougat)

Parameters
identity Int: the identity value for the accumulating function
op Int: an associative, non-interfering, stateless function for combining two values
Return
Int: the result of the reduction

reduce

added in API level 24
abstract fun reduce(op: IntBinaryOperator!): OptionalInt!

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

boolean foundAny = false; int result = null; for (int element : this stream) { if (!foundAny) { foundAny = true; result = element; } else result = accumulator.applyAsInt(result, element); } return foundAny ? OptionalInt.of(result) : OptionalInt.empty(); 
but is not constrained to execute sequentially.

The accumulator function must be an associative function.

This is a terminal operation.
Requires API level 24 (Android 7.0, Nougat)

Parameters
op IntBinaryOperator!: an associative, non-interfering, stateless function for combining two values
Return
OptionalInt!: the result of the reduction

sequential

added in API level 24
abstract fun sequential(): IntStream!

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.
Requires API level 24 (Android 7.0, Nougat) Requires API level 24 (Android 7.0, Nougat)

Return
IntStream!: a sequential stream

count

added in API level 24
abstract fun count(): Long

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

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

This is a terminal operation.
Requires API level 24 (Android 7.0, Nougat)

Return
Long: the count of elements in this stream

anyMatch

added in API level 24
abstract fun anyMatch(predicate: IntPredicate!): Boolean

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.
Requires API level 24 (Android 7.0, Nougat)

Parameters
predicate IntPredicate!: a non-interfering, stateless predicate to apply to elements of this stream
Return
Boolean: true if any elements of the stream match the provided predicate, otherwise false

findAny

added in API level 24
abstract fun findAny(): OptionalInt!

Returns an OptionalInt describing some element of the stream, or an empty OptionalInt 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.)
Requires API level 24 (Android 7.0, Nougat)

Return
OptionalInt!: an OptionalInt describing some element of this stream, or an empty OptionalInt if the stream is empty

See Also

iterator

added in API level 24
abstract fun iterator(): PrimitiveIterator.OfInt!

Returns an iterator for the elements of this stream.

This is a terminal operation.
Requires API level 24 (Android 7.0, Nougat) Requires API level 24 (Android 7.0, Nougat)

Return
PrimitiveIterator.OfInt!: the element iterator for this stream

map

added in API level 24
abstract fun map(mapper: IntUnaryOperator!): IntStream!

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

This is an intermediate operation.
Requires API level 24 (Android 7.0, Nougat)

Parameters
mapper IntUnaryOperator!: a non-interfering, stateless function to apply to each element
Return
IntStream!: the new stream

filter

added in API level 24
abstract fun filter(predicate: IntPredicate!): IntStream!

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

This is an intermediate operation.
Requires API level 24 (Android 7.0, Nougat)

Parameters
predicate IntPredicate!: a non-interfering, stateless predicate to apply to each element to determine if it should be included
Return
IntStream!: the new stream

summaryStatistics

added in API level 24
abstract fun summaryStatistics(): IntSummaryStatistics!

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

This is a terminal operation.
Requires API level 24 (Android 7.0, Nougat)

Return
IntSummaryStatistics!: an IntSummaryStatistics describing various summary data about the elements of this stream

boxed

added in API level 24
abstract fun boxed(): Stream<Int!>!

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

This is an intermediate operation.
Requires API level 24 (Android 7.0, Nougat)

Return
Stream<Int!>!: a Stream consistent of the elements of this stream, each boxed to an Integer

flatMap

added in API level 24
abstract fun flatMap(mapper: IntFunction<out IntStream!>!): IntStream!

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.
Requires API level 24 (Android 7.0, Nougat)

Parameters
mapper IntFunction<out IntStream!>!: a non-interfering, stateless function to apply to each element which produces an IntStream of new values
Return
IntStream!: the new stream

forEach

added in API level 24
abstract fun forEach(action: IntConsumer!): Unit

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.
Requires API level 24 (Android 7.0, Nougat)

Parameters
action IntConsumer!: a non-interfering action to perform on the elements

peek

added in API level 24
abstract fun peek(action: IntConsumer!): IntStream!

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.
Requires API level 24 (Android 7.0, Nougat)

Parameters
action IntConsumer!: a non-interfering action to perform on the elements as they are consumed from the stream
Return
IntStream!: the new stream

allMatch

added in API level 24
abstract fun allMatch(predicate: IntPredicate!): Boolean

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.
Requires API level 24 (Android 7.0, Nougat)

Parameters
predicate IntPredicate!: a non-interfering, stateless predicate to apply to elements of this stream
Return
Boolean: true if either all elements of the stream match the provided predicate or the stream is empty, otherwise false

findFirst

added in API level 24
abstract fun findFirst(): OptionalInt!

Returns an OptionalInt describing the first element of this stream, or an empty OptionalInt 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.
Requires API level 24 (Android 7.0, Nougat)

Return
OptionalInt!: an OptionalInt describing the first element of this stream, or an empty OptionalInt if the stream is empty

min

added in API level 24
abstract fun min(): OptionalInt!

Returns an OptionalInt 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(Integer::min); 

This is a terminal operation.
Requires API level 24 (Android 7.0, Nougat)

Return
OptionalInt!: an OptionalInt containing the minimum element of this stream, or an empty OptionalInt if the stream is empty

spliterator

added in API level 24
abstract fun spliterator(): Spliterator.OfInt!

Returns a spliterator for the elements of this stream.

This is a terminal operation.
Requires API level 24 (Android 7.0, Nougat) Requires API level 24 (Android 7.0, Nougat)

Return
Spliterator.OfInt!: the element spliterator for this stream

toArray

added in API level 24
abstract fun toArray(): IntArray!

Returns an array containing the elements of this stream.

This is a terminal operation.
Requires API level 24 (Android 7.0, Nougat)

Return
IntArray!: an array containing the elements of this stream

asDoubleStream

added in API level 24
abstract fun asDoubleStream(): DoubleStream!

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

This is an intermediate operation.
Requires API level 24 (Android 7.0, Nougat)

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

limit

added in API level 24
abstract fun limit(maxSize: Long): IntStream!

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.
Requires API level 24 (Android 7.0, Nougat)

Parameters
maxSize Long: the number of elements the stream should be limited to
Return
IntStream!: the new stream
Exceptions
IllegalArgumentException if maxSize is negative

sum

added in API level 24
abstract fun sum(): Int

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

return reduce(0, Integer::sum); 

This is a terminal operation.
Requires API level 24 (Android 7.0, Nougat)

Return
Int: the sum of elements in this stream

forEachOrdered

added in API level 24
abstract fun forEachOrdered(action: IntConsumer!): Unit

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.
Requires API level 24 (Android 7.0, Nougat)

Parameters
action IntConsumer!: a non-interfering action to perform on the elements

skip

added in API level 24
abstract fun skip(n: Long): IntStream!

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.
Requires API level 24 (Android 7.0, Nougat)

Parameters
n Long: the number of leading elements to skip
Return
IntStream!: the new stream
Exceptions
IllegalArgumentException if n is negative

parallel

added in API level 24
abstract fun parallel(): IntStream!

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.
Requires API level 24 (Android 7.0, Nougat) Requires API level 24 (Android 7.0, Nougat)

Return
IntStream!: a parallel stream

mapToDouble

added in API level 24
abstract fun mapToDouble(mapper: IntToDoubleFunction!): DoubleStream!

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

This is an intermediate operation.
Requires API level 24 (Android 7.0, Nougat)

Parameters
mapper IntToDoubleFunction!: a non-interfering, stateless function to apply to each element
Return
DoubleStream!: the new stream

max

added in API level 24
abstract fun max(): OptionalInt!

Returns an OptionalInt 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(Integer::max); 

This is a terminal operation.
Requires API level 24 (Android 7.0, Nougat)

Return
OptionalInt!: an OptionalInt containing the maximum element of this stream, or an empty OptionalInt if the stream is empty

asLongStream

added in API level 24
abstract fun asLongStream(): LongStream!

Returns a LongStream consisting of the elements of this stream, converted to long.

This is an intermediate operation.
Requires API level 24 (Android 7.0, Nougat)

Return
LongStream!: a LongStream consisting of the elements of this stream, converted to long

sorted

added in API level 24
abstract fun sorted(): IntStream!

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

This is a stateful intermediate operation.
Requires API level 24 (Android 7.0, Nougat)

Return
IntStream!: the new stream

noneMatch

added in API level 24
abstract fun noneMatch(predicate: IntPredicate!): Boolean

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.
Requires API level 24 (Android 7.0, Nougat)

Parameters
predicate IntPredicate!: a non-interfering, stateless predicate to apply to elements of this stream
Return
Boolean: true if either no elements of the stream match the provided predicate or the stream is empty, otherwise false

distinct

added in API level 24
abstract fun distinct(): IntStream!

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

This is a stateful intermediate operation.
Requires API level 24 (Android 7.0, Nougat)

Return
IntStream!: the new stream

average

added in API level 24
abstract fun average(): OptionalDouble!

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.
Requires API level 24 (Android 7.0, Nougat)

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

builder

added in API level 24
open static fun builder(): IntStream.Builder!

Returns a builder for an IntStream.
Requires API level 24 (Android 7.0, Nougat)

Return
IntStream.Builder!: a stream builder

empty

added in API level 24
open static fun empty(): IntStream!

Returns an empty sequential IntStream.
Requires API level 24 (Android 7.0, Nougat)

Return
IntStream!: an empty sequential stream

of

added in API level 24
open static fun of(t: Int): IntStream!

Returns a sequential IntStream containing a single element.
Requires API level 24 (Android 7.0, Nougat)

Parameters
t Int: the single element
Return
IntStream!: a singleton sequential stream

of

added in API level 24
open static fun of(vararg values: Int): IntStream!

Returns a sequential ordered stream whose elements are the specified values.
Requires API level 24 (Android 7.0, Nougat)

Parameters
values Int: the elements of the new stream
Return
IntStream!: the new stream

iterate

added in API level 24
open static fun iterate(seed: Int, f: IntUnaryOperator!): IntStream!

Returns an infinite sequential ordered IntStream 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 IntStream 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.
Requires API level 24 (Android 7.0, Nougat)

Parameters
seed Int: the initial element
f Int: a function to be applied to to the previous element to produce a new element
Return
IntStream!: A new sequential IntStream

generate

added in API level 24
open static fun generate(s: IntSupplier!): IntStream!

Returns an infinite sequential unordered stream where each element is generated by the provided IntSupplier. This is suitable for generating constant streams, streams of random elements, etc.
Requires API level 24 (Android 7.0, Nougat)

Parameters
s IntSupplier!: the IntSupplier for generated elements
Return
IntStream!: a new infinite sequential unordered IntStream

range

added in API level 24
open static fun range(startInclusive: Int, endExclusive: Int): IntStream!

Returns a sequential ordered IntStream from startInclusive (inclusive) to endExclusive (exclusive) by an incremental step of 1.
Requires API level 24 (Android 7.0, Nougat)

Parameters
startInclusive Int: the (inclusive) initial value
endExclusive Int: the exclusive upper bound
Return
IntStream!: a sequential IntStream for the range of int elements

rangeClosed

added in API level 24
open static fun rangeClosed(startInclusive: Int, endInclusive: Int): IntStream!

Returns a sequential ordered IntStream from startInclusive (inclusive) to endInclusive (inclusive) by an incremental step of 1.
Requires API level 24 (Android 7.0, Nougat)

Parameters
startInclusive Int: the (inclusive) initial value
endInclusive Int: the inclusive upper bound
Return
IntStream!: a sequential IntStream for the range of int elements

concat

added in API level 24
open static fun concat(a: IntStream!, b: IntStream!): IntStream!

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.
Requires API level 24 (Android 7.0, Nougat)

Parameters
a IntStream!: the first stream
b IntStream!: the second stream
Return
IntStream!: the concatenation of the two input streams