public interface IntStream extends BaseStream<Integer,IntStream>
int
primitive specialization of
Stream
.
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.Stream
,
java.util.streamModifier and Type  Interface and Description 

static interface 
IntStream.Builder
A mutable builder for an
IntStream . 
Modifier and Type  Method and Description 

boolean 
allMatch(IntPredicate predicate)
Returns whether all elements of this stream match the provided predicate.

boolean 
anyMatch(IntPredicate predicate)
Returns whether any elements of this stream match the provided
predicate.

DoubleStream 
asDoubleStream()
Returns a
DoubleStream consisting of the elements of this stream,
converted to double . 
LongStream 
asLongStream()
Returns a
LongStream consisting of the elements of this stream,
converted to long . 
OptionalDouble 
average()
Returns an
OptionalDouble describing the arithmetic mean of elements of
this stream, or an empty optional if this stream is empty. 
Stream<Integer> 
boxed()
Returns a
Stream consisting of the elements of this stream,
each boxed to an Integer . 
static IntStream.Builder 
builder()
Returns a builder for an
IntStream . 
<R> R 
collect(Supplier<R> supplier,
ObjIntConsumer<R> accumulator,
BiConsumer<R,R> combiner)
Performs a mutable
reduction operation on the elements of this stream.

static IntStream 
concat(IntStream a,
IntStream 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.

long 
count()
Returns the count of elements in this stream.

IntStream 
distinct()
Returns a stream consisting of the distinct elements of this stream.

static IntStream 
empty()
Returns an empty sequential
IntStream . 
IntStream 
filter(IntPredicate predicate)
Returns a stream consisting of the elements of this stream that match
the given predicate.

OptionalInt 
findAny()
Returns an
OptionalInt describing some element of the stream, or
an empty OptionalInt if the stream is empty. 
OptionalInt 
findFirst()
Returns an
OptionalInt describing the first element of this
stream, or an empty OptionalInt if the stream is empty. 
IntStream 
flatMap(IntFunction<? extends IntStream> 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.

void 
forEach(IntConsumer action)
Performs an action for each element of this stream.

void 
forEachOrdered(IntConsumer 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.

static IntStream 
generate(IntSupplier s)
Returns an infinite sequential unordered stream where each element is
generated by the provided
IntSupplier . 
static IntStream 
iterate(int seed,
IntUnaryOperator f)
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. 
PrimitiveIterator.OfInt 
iterator()
Returns an iterator for the elements of this stream.

IntStream 
limit(long maxSize)
Returns a stream consisting of the elements of this stream, truncated
to be no longer than
maxSize in length. 
IntStream 
map(IntUnaryOperator mapper)
Returns a stream consisting of the results of applying the given
function to the elements of this stream.

DoubleStream 
mapToDouble(IntToDoubleFunction mapper)
Returns a
DoubleStream consisting of the results of applying the
given function to the elements of this stream. 
LongStream 
mapToLong(IntToLongFunction mapper)
Returns a
LongStream consisting of the results of applying the
given function to the elements of this stream. 
<U> Stream<U> 
mapToObj(IntFunction<? extends U> mapper)
Returns an objectvalued
Stream consisting of the results of
applying the given function to the elements of this stream. 
OptionalInt 
max()
Returns an
OptionalInt describing the maximum element of this
stream, or an empty optional if this stream is empty. 
OptionalInt 
min()
Returns an
OptionalInt describing the minimum element of this
stream, or an empty optional if this stream is empty. 
boolean 
noneMatch(IntPredicate predicate)
Returns whether no elements of this stream match the provided predicate.

static IntStream 
of(int... values)
Returns a sequential ordered stream whose elements are the specified values.

static IntStream 
of(int t)
Returns a sequential
IntStream containing a single element. 
IntStream 
parallel()
Returns an equivalent stream that is parallel.

IntStream 
peek(IntConsumer 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.

static IntStream 
range(int startInclusive,
int endExclusive)
Returns a sequential ordered
IntStream from startInclusive
(inclusive) to endExclusive (exclusive) by an incremental step of
1 . 
static IntStream 
rangeClosed(int startInclusive,
int endInclusive)
Returns a sequential ordered
IntStream from startInclusive
(inclusive) to endInclusive (inclusive) by an incremental step of
1 . 
OptionalInt 
reduce(IntBinaryOperator op)
Performs a reduction on the
elements of this stream, using an
associative accumulation
function, and returns an
OptionalInt describing the reduced value,
if any. 
int 
reduce(int identity,
IntBinaryOperator 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.

IntStream 
sequential()
Returns an equivalent stream that is sequential.

IntStream 
skip(long n)
Returns a stream consisting of the remaining elements of this stream
after discarding the first
n elements of the stream. 
IntStream 
sorted()
Returns a stream consisting of the elements of this stream in sorted
order.

Spliterator.OfInt 
spliterator()
Returns a spliterator for the elements of this stream.

int 
sum()
Returns the sum of elements in this stream.

IntSummaryStatistics 
summaryStatistics()
Returns an
IntSummaryStatistics describing various
summary data about the elements of this stream. 
int[] 
toArray()
Returns an array containing the elements of this stream.

close, isParallel, onClose, unordered
IntStream filter(IntPredicate predicate)
This is an intermediate operation.
predicate
 a noninterfering,
stateless
predicate to apply to each element to determine if it
should be includedIntStream map(IntUnaryOperator mapper)
This is an intermediate operation.
mapper
 a noninterfering,
stateless
function to apply to each element<U> Stream<U> mapToObj(IntFunction<? extends U> mapper)
Stream
consisting of the results of
applying the given function to the elements of this stream.
This is an intermediate operation.
U
 the element type of the new streammapper
 a noninterfering,
stateless
function to apply to each elementLongStream mapToLong(IntToLongFunction mapper)
LongStream
consisting of the results of applying the
given function to the elements of this stream.
This is an intermediate operation.
mapper
 a noninterfering,
stateless
function to apply to each elementDoubleStream mapToDouble(IntToDoubleFunction mapper)
DoubleStream
consisting of the results of applying the
given function to the elements of this stream.
This is an intermediate operation.
mapper
 a noninterfering,
stateless
function to apply to each elementIntStream flatMap(IntFunction<? extends IntStream> mapper)
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.
mapper
 a noninterfering,
stateless
function to apply to each element which produces an
IntStream
of new valuesStream.flatMap(Function)
IntStream distinct()
This is a stateful intermediate operation.
IntStream sorted()
This is a stateful intermediate operation.
IntStream peek(IntConsumer action)
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.
IntStream.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();
action
 a
noninterfering action to perform on the elements as
they are consumed from the streamIntStream limit(long maxSize)
maxSize
in length.
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(IntSupplier)
) or removing the
ordering constraint with BaseStream.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.maxSize
 the number of elements the stream should be limited toIllegalArgumentException
 if maxSize
is negativeIntStream skip(long n)
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.
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(IntSupplier)
) or removing the
ordering constraint with BaseStream.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.n
 the number of leading elements to skipIllegalArgumentException
 if n
is negativevoid forEach(IntConsumer action)
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.
action
 a
noninterfering action to perform on the elementsvoid forEachOrdered(IntConsumer action)
This is a terminal operation.
action
 a
noninterfering action to perform on the elementsforEach(IntConsumer)
int[] toArray()
This is a terminal operation.
int reduce(int identity, IntBinaryOperator op)
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.
int sum = integers.reduce(0, (a, b) > a+b);
or more compactly:
int sum = integers.reduce(0, Integer::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.
identity
 the identity value for the accumulating functionop
 an associative,
noninterfering,
stateless
function for combining two valuessum()
,
min()
,
max()
,
average()
OptionalInt reduce(IntBinaryOperator op)
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.
op
 an associative,
noninterfering,
stateless
function for combining two valuesreduce(int, IntBinaryOperator)
<R> R collect(Supplier<R> supplier, ObjIntConsumer<R> accumulator, BiConsumer<R,R> combiner)
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.
R
 type of the resultsupplier
 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
 an associative,
noninterfering,
stateless
function for incorporating an additional element into a resultcombiner
 an associative,
noninterfering,
stateless
function for combining two values, which must be
compatible with the accumulator functionStream.collect(Supplier, BiConsumer, BiConsumer)
int sum()
return reduce(0, Integer::sum);
This is a terminal operation.
OptionalInt min()
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.
OptionalInt
containing the minimum element of this
stream, or an empty OptionalInt
if the stream is emptyOptionalInt max()
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.
OptionalInt
containing the maximum element of this
stream, or an empty OptionalInt
if the stream is emptylong count()
return mapToLong(e > 1L).sum();
This is a terminal operation.
OptionalDouble average()
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.
OptionalDouble
containing the average element of this
stream, or an empty optional if the stream is emptyIntSummaryStatistics summaryStatistics()
IntSummaryStatistics
describing various
summary data about the elements of this stream. This is a special
case of a reduction.
This is a terminal operation.
IntSummaryStatistics
describing various summary data
about the elements of this streamboolean anyMatch(IntPredicate predicate)
false
is returned and the predicate is not evaluated.
This is a shortcircuiting terminal operation.
predicate
 a noninterfering,
stateless
predicate to apply to elements of this streamtrue
if any elements of the stream match the provided
predicate, otherwise false
boolean allMatch(IntPredicate predicate)
true
is
returned and the predicate is not evaluated.
This is a shortcircuiting terminal operation.
true
(regardless of P(x)).predicate
 a noninterfering,
stateless
predicate to apply to elements of this streamtrue
if either all elements of the stream match the
provided predicate or the stream is empty, otherwise false
boolean noneMatch(IntPredicate predicate)
true
is
returned and the predicate is not evaluated.
This is a shortcircuiting terminal operation.
true
, regardless of P(x).predicate
 a noninterfering,
stateless
predicate to apply to elements of this streamtrue
if either no elements of the stream match the
provided predicate or the stream is empty, otherwise false
OptionalInt findFirst()
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 shortcircuiting terminal operation.
OptionalInt
describing the first element of this stream,
or an empty OptionalInt
if the stream is emptyOptionalInt findAny()
OptionalInt
describing some element of the stream, or
an empty OptionalInt
if the stream is empty.
This is a shortcircuiting 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.)
OptionalInt
describing some element of this stream, or
an empty OptionalInt
if the stream is emptyfindFirst()
LongStream asLongStream()
LongStream
consisting of the elements of this stream,
converted to long
.
This is an intermediate operation.
LongStream
consisting of the elements of this stream,
converted to long
DoubleStream asDoubleStream()
DoubleStream
consisting of the elements of this stream,
converted to double
.
This is an intermediate operation.
DoubleStream
consisting of the elements of this stream,
converted to double
Stream<Integer> boxed()
Stream
consisting of the elements of this stream,
each boxed to an Integer
.
This is an intermediate operation.
Stream
consistent of the elements of this stream,
each boxed to an Integer
IntStream sequential()
BaseStream
This is an intermediate operation.
sequential
in interface BaseStream<Integer,IntStream>
IntStream parallel()
BaseStream
This is an intermediate operation.
parallel
in interface BaseStream<Integer,IntStream>
PrimitiveIterator.OfInt iterator()
BaseStream
This is a terminal operation.
iterator
in interface BaseStream<Integer,IntStream>
Spliterator.OfInt spliterator()
BaseStream
This is a terminal operation.
spliterator
in interface BaseStream<Integer,IntStream>
static IntStream.Builder builder()
IntStream
.static IntStream empty()
IntStream
.static IntStream of(int t)
IntStream
containing a single element.t
 the single elementstatic IntStream of(int... values)
values
 the elements of the new streamstatic IntStream iterate(int seed, IntUnaryOperator f)
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
.
seed
 the initial elementf
 a function to be applied to the previous element to produce
a new elementIntStream
static IntStream generate(IntSupplier s)
IntSupplier
. This is suitable for
generating constant streams, streams of random elements, etc.s
 the IntSupplier
for generated elementsIntStream
static IntStream range(int startInclusive, int endExclusive)
IntStream
from startInclusive
(inclusive) to endExclusive
(exclusive) by an incremental step of
1
.An equivalent sequence of increasing values can be produced
sequentially using a for
loop as follows:
for (int i = startInclusive; i < endExclusive ; i++) { ... }
startInclusive
 the (inclusive) initial valueendExclusive
 the exclusive upper boundIntStream
for the range of int
elementsstatic IntStream rangeClosed(int startInclusive, int endInclusive)
IntStream
from startInclusive
(inclusive) to endInclusive
(inclusive) by an incremental step of
1
.An equivalent sequence of increasing values can be produced
sequentially using a for
loop as follows:
for (int i = startInclusive; i <= endInclusive ; i++) { ... }
startInclusive
 the (inclusive) initial valueendInclusive
 the inclusive upper boundIntStream
for the range of int
elementsstatic IntStream concat(IntStream a, IntStream b)
StackOverflowException
.a
 the first streamb
 the second stream Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developertargeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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