Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) Summary: [Nested Classes](https://developer.android.com/reference/java/util/stream/Stream#nestedclasses) \| [Methods](https://developer.android.com/reference/java/util/stream/Stream#pubmethods) \| [Inherited Methods](https://developer.android.com/reference/java/util/stream/Stream#inhmethods)

# Stream


`
public


interface
Stream
`


`


implements

https://developer.android.com/reference/java/util/stream/BaseStream<T, https://developer.android.com/reference/java/util/stream/Stream<T>>


`

|---|
| java.util.stream.Stream\<T\> |

<br />

*** ** * ** ***

A sequence of elements supporting sequential and parallel aggregate
operations. The following example illustrates an aggregate operation using
`https://developer.android.com/reference/java/util/stream/Stream` and `https://developer.android.com/reference/java/util/stream/IntStream`:

    int sum = widgets.stream()
                         .filter(w -> w.getColor() == RED)
                         .mapToInt(w -> w.getWeight())
                         .sum();

In this example, `widgets` is a `Collection<Widget>`. We create a stream of `Widget` objects via `https://developer.android.com/reference/java/util/Collection#stream()`, filter it to produce a stream containing only the red widgets, and then transform it into a stream of `int` values representing the weight of each red widget. Then this stream is summed to produce a total weight.

In addition to `Stream`, which is a stream of object references,
there are primitive specializations for `https://developer.android.com/reference/java/util/stream/IntStream`, `https://developer.android.com/reference/java/util/stream/LongStream`,
and `https://developer.android.com/reference/java/util/stream/DoubleStream`, all of which are referred to as "streams" and
conform to the characteristics and restrictions described here.

To perform a computation, stream
[operations](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps) are composed into a
*stream pipeline* . A stream pipeline consists of a source (which
might be an array, a collection, a generator function, an I/O channel,
etc), zero or more *intermediate operations* (which transform a
stream into another stream, such as `https://developer.android.com/reference/java/util/stream/Stream#filter(java.util.function.Predicate<?%20super%20T>)`), and a
*terminal operation* (which produces a result or side-effect, such
as `https://developer.android.com/reference/java/util/stream/Stream#count()` or `https://developer.android.com/reference/java/util/stream/Stream#forEach(java.util.function.Consumer<?%20super%20T>)`).
Streams are lazy; computation on the source data is only performed when the
terminal operation is initiated, and source elements are consumed only
as needed.

A stream implementation is permitted significant latitude in optimizing
the computation of the result. For example, a stream implementation is free
to elide operations (or entire stages) from a stream pipeline -- and
therefore elide invocation of behavioral parameters -- if it can prove that
it would not affect the result of the computation. This means that
side-effects of behavioral parameters may not always be executed and should
not be relied upon, unless otherwise specified (such as by the terminal
operations `forEach` and `forEachOrdered`). (For a specific
example of such an optimization, see the API note documented on the
`https://developer.android.com/reference/java/util/stream/Stream#count()` operation. For more detail, see the
[side-effects](https://developer.android.com/reference/java/util/stream/package-summary#SideEffects) section of the
stream package documentation.)

Collections and streams, while bearing some superficial similarities,
have different goals. Collections are primarily concerned with the efficient
management of, and access to, their elements. By contrast, streams do not
provide a means to directly access or manipulate their elements, and are
instead concerned with declaratively describing their source and the
computational operations which will be performed in aggregate on that source.
However, if the provided stream operations do not offer the desired
functionality, the `https://developer.android.com/reference/java/util/stream/BaseStream#iterator()` and `https://developer.android.com/reference/java/util/stream/BaseStream#spliterator()` operations
can be used to perform a controlled traversal.

A stream pipeline, like the "widgets" example above, can be viewed as
a *query* on the stream source. Unless the source was explicitly
designed for concurrent modification (such as a `https://developer.android.com/reference/java/util/concurrent/ConcurrentHashMap`),
unpredictable or erroneous behavior may result from modifying the stream
source while it is being queried.

Most stream operations accept parameters that describe user-specified
behavior, such as the lambda expression `w -> w.getWeight()` passed to
`mapToInt` in the example above. To preserve correct behavior,
these *behavioral parameters*:

- must be [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference) (they do not modify the stream source); and
- in most cases must be [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) (their result should not depend on any state that might change during execution of the stream pipeline).

Such parameters are always instances of a
[functional interface](https://developer.android.com/reference/java/util/function/package-summary.html) such
as `https://developer.android.com/reference/java/util/function/Function`, and are often lambda expressions or
method references. Unless otherwise specified these parameters must be
*non-null*.

A stream should be operated on (invoking an intermediate or terminal stream
operation) only once. This rules out, for example, "forked" streams, where
the same source feeds two or more pipelines, or multiple traversals of the
same stream. A stream implementation may throw `https://developer.android.com/reference/java/lang/IllegalStateException`
if it detects that the stream is being reused. However, since some stream
operations may return their receiver rather than a new stream object, it may
not be possible to detect reuse in all cases.

Streams have a `https://developer.android.com/reference/java/util/stream/BaseStream#close()` method and implement `https://developer.android.com/reference/java/lang/AutoCloseable`.
Operating on a stream after it has been closed will throw `https://developer.android.com/reference/java/lang/IllegalStateException`.
Most stream instances do not actually need to be closed after use, as they
are backed by collections, arrays, or generating functions, which require no
special resource management. Generally, only streams whose source is an IO channel,
such as those returned by `https://developer.android.com/reference/java/nio/file/Files#lines(java.nio.file.Path)`, will require closing. If a
stream does require closing, it must be opened as a resource within a try-with-resources
statement or similar control structure to ensure that it is closed promptly after its
operations have completed.

Stream pipelines may execute either sequentially or in
[parallel](https://developer.android.com/reference/java/util/stream/package-summary#Parallelism). This
execution mode is a property of the stream. Streams are created
with an initial choice of sequential or parallel execution. (For example,
`https://developer.android.com/reference/java/util/Collection#stream()` creates a sequential stream,
and `https://developer.android.com/reference/java/util/Collection#parallelStream()` creates
a parallel one.) This choice of execution mode may be modified by the
`https://developer.android.com/reference/java/util/stream/BaseStream#sequential()` or `https://developer.android.com/reference/java/util/stream/BaseStream#parallel()` methods, and may be queried with
the `https://developer.android.com/reference/java/util/stream/BaseStream#isParallel()` method.
**See also:**

- `https://developer.android.com/reference/java/util/stream/IntStream`
- `https://developer.android.com/reference/java/util/stream/LongStream`
- `https://developer.android.com/reference/java/util/stream/DoubleStream`
- [java.util.stream](https://developer.android.com/reference/java/util/stream/package-summary)

## Summary

| ### Nested classes ||
|---|---|
| ` interface` | `https://developer.android.com/reference/java/util/stream/Stream.Builder<T>` A mutable builder for a `Stream`. |

| ### Public methods ||
|---|---|
| ` abstract boolean` | ` https://developer.android.com/reference/java/util/stream/Stream#allMatch(java.util.function.Predicate<?%20super%20T>)(https://developer.android.com/reference/java/util/function/Predicate<? super T> predicate) ` Returns whether all elements of this stream match the provided predicate. |
| ` abstract boolean` | ` https://developer.android.com/reference/java/util/stream/Stream#anyMatch(java.util.function.Predicate<?%20super%20T>)(https://developer.android.com/reference/java/util/function/Predicate<? super T> predicate) ` Returns whether any elements of this stream match the provided predicate. |
| ` static <T> https://developer.android.com/reference/java/util/stream/Stream.Builder<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#builder()() ` Returns a builder for a `Stream`. |
| ` abstract <R> R` | ` https://developer.android.com/reference/java/util/stream/Stream#collect(java.util.function.Supplier<R>,%20java.util.function.BiConsumer<R,?%20super%20T>,%20java.util.function.BiConsumer<R,R>)(https://developer.android.com/reference/java/util/function/Supplier<R> supplier, https://developer.android.com/reference/java/util/function/BiConsumer<R, ? super T> accumulator, https://developer.android.com/reference/java/util/function/BiConsumer<R, R> combiner) ` Performs a [mutable reduction](https://developer.android.com/reference/java/util/stream/package-summary#MutableReduction) operation on the elements of this stream. |
| ` abstract <R, A> R` | ` https://developer.android.com/reference/java/util/stream/Stream#collect(java.util.stream.Collector<?%20super%20T,A,R>)(https://developer.android.com/reference/java/util/stream/Collector<? super T, A, R> collector) ` Performs a [mutable reduction](https://developer.android.com/reference/java/util/stream/package-summary#MutableReduction) operation on the elements of this stream using a `Collector`. |
| ` static <T> https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#concat(java.util.stream.Stream<?%20extends%20T>,%20java.util.stream.Stream<?%20extends%20T>)(https://developer.android.com/reference/java/util/stream/Stream<? extends T> a, https://developer.android.com/reference/java/util/stream/Stream<? extends T> 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. |
| ` abstract long` | ` https://developer.android.com/reference/java/util/stream/Stream#count()() ` Returns the count of elements in this stream. |
| ` abstract https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#distinct()() ` Returns a stream consisting of the distinct elements (according to `https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object)`) of this stream. |
| ` default https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#dropWhile(java.util.function.Predicate<?%20super%20T>)(https://developer.android.com/reference/java/util/function/Predicate<? super T> 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. |
| ` static <T> https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#empty()() ` Returns an empty sequential `Stream`. |
| ` abstract https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#filter(java.util.function.Predicate<?%20super%20T>)(https://developer.android.com/reference/java/util/function/Predicate<? super T> predicate) ` Returns a stream consisting of the elements of this stream that match the given predicate. |
| ` abstract https://developer.android.com/reference/java/util/Optional<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#findAny()() ` Returns an `https://developer.android.com/reference/java/util/Optional` describing some element of the stream, or an empty `Optional` if the stream is empty. |
| ` abstract https://developer.android.com/reference/java/util/Optional<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#findFirst()() ` Returns an `https://developer.android.com/reference/java/util/Optional` describing the first element of this stream, or an empty `Optional` if the stream is empty. |
| ` abstract <R> https://developer.android.com/reference/java/util/stream/Stream<R>` | ` https://developer.android.com/reference/java/util/stream/Stream#flatMap(java.util.function.Function<?%20super%20T,?%20extends%20java.util.stream.Stream<?%20extends%20R>>)(https://developer.android.com/reference/java/util/function/Function<? super T, ? extends https://developer.android.com/reference/java/util/stream/Stream<? extends R>> 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. |
| ` abstract https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/Stream#flatMapToDouble(java.util.function.Function<?%20super%20T,?%20extends%20java.util.stream.DoubleStream>)(https://developer.android.com/reference/java/util/function/Function<? super T, ? extends https://developer.android.com/reference/java/util/stream/DoubleStream> mapper) ` Returns an `DoubleStream` 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 https://developer.android.com/reference/java/util/stream/IntStream` | ` https://developer.android.com/reference/java/util/stream/Stream#flatMapToInt(java.util.function.Function<?%20super%20T,?%20extends%20java.util.stream.IntStream>)(https://developer.android.com/reference/java/util/function/Function<? super T, ? extends https://developer.android.com/reference/java/util/stream/IntStream> mapper) ` Returns an `IntStream` 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 https://developer.android.com/reference/java/util/stream/LongStream` | ` https://developer.android.com/reference/java/util/stream/Stream#flatMapToLong(java.util.function.Function<?%20super%20T,?%20extends%20java.util.stream.LongStream>)(https://developer.android.com/reference/java/util/function/Function<? super T, ? extends https://developer.android.com/reference/java/util/stream/LongStream> mapper) ` Returns an `LongStream` 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 void` | ` https://developer.android.com/reference/java/util/stream/Stream#forEach(java.util.function.Consumer<?%20super%20T>)(https://developer.android.com/reference/java/util/function/Consumer<? super T> action) ` Performs an action for each element of this stream. |
| ` abstract void` | ` https://developer.android.com/reference/java/util/stream/Stream#forEachOrdered(java.util.function.Consumer<?%20super%20T>)(https://developer.android.com/reference/java/util/function/Consumer<? super T> action) ` Performs an action for each element of this stream, in the encounter order of the stream if the stream has a defined encounter order. |
| ` default <R> https://developer.android.com/reference/java/util/stream/Stream<R>` | ` https://developer.android.com/reference/java/util/stream/Stream#gather(java.util.stream.Gatherer<?%20super%20T,?,R>)(https://developer.android.com/reference/java/util/stream/Gatherer<? super T, ?, R> gatherer) ` Returns a stream consisting of the results of applying the given `https://developer.android.com/reference/java/util/stream/Gatherer` to the elements of this stream. |
| ` static <T> https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#generate(java.util.function.Supplier<?%20extends%20T>)(https://developer.android.com/reference/java/util/function/Supplier<? extends T> s) ` Returns an infinite sequential unordered stream where each element is generated by the provided `Supplier`. |
| ` static <T> https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#iterate(T,%20java.util.function.UnaryOperator<T>)(T seed, https://developer.android.com/reference/java/util/function/UnaryOperator<T> f) ` Returns an infinite sequential ordered `Stream` 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. |
| ` static <T> https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#iterate(T,%20java.util.function.Predicate<?%20super%20T>,%20java.util.function.UnaryOperator<T>)(T seed, https://developer.android.com/reference/java/util/function/Predicate<? super T> hasNext, https://developer.android.com/reference/java/util/function/UnaryOperator<T> next) ` Returns a sequential ordered `Stream` produced by iterative application of the given `next` function to an initial element, conditioned on satisfying the given `hasNext` predicate. |
| ` abstract https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#limit(long)(long maxSize) ` Returns a stream consisting of the elements of this stream, truncated to be no longer than `maxSize` in length. |
| ` abstract <R> https://developer.android.com/reference/java/util/stream/Stream<R>` | ` https://developer.android.com/reference/java/util/stream/Stream#map(java.util.function.Function<?%20super%20T,?%20extends%20R>)(https://developer.android.com/reference/java/util/function/Function<? super T, ? extends R> mapper) ` Returns a stream consisting of the results of applying the given function to the elements of this stream. |
| ` default <R> https://developer.android.com/reference/java/util/stream/Stream<R>` | ` https://developer.android.com/reference/java/util/stream/Stream#mapMulti(java.util.function.BiConsumer<?%20super%20T,?%20super%20java.util.function.Consumer<R>>)(https://developer.android.com/reference/java/util/function/BiConsumer<? super T, ? super https://developer.android.com/reference/java/util/function/Consumer<R>> mapper) ` Returns a stream consisting of the results of replacing each element of this stream with multiple elements, specifically zero or more elements. |
| ` default https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/Stream#mapMultiToDouble(java.util.function.BiConsumer<?%20super%20T,?%20super%20java.util.function.DoubleConsumer>)(https://developer.android.com/reference/java/util/function/BiConsumer<? super T, ? super https://developer.android.com/reference/java/util/function/DoubleConsumer> mapper) ` Returns a `DoubleStream` consisting of the results of replacing each element of this stream with multiple elements, specifically zero or more elements. |
| ` default https://developer.android.com/reference/java/util/stream/IntStream` | ` https://developer.android.com/reference/java/util/stream/Stream#mapMultiToInt(java.util.function.BiConsumer<?%20super%20T,?%20super%20java.util.function.IntConsumer>)(https://developer.android.com/reference/java/util/function/BiConsumer<? super T, ? super https://developer.android.com/reference/java/util/function/IntConsumer> mapper) ` Returns an `IntStream` consisting of the results of replacing each element of this stream with multiple elements, specifically zero or more elements. |
| ` default https://developer.android.com/reference/java/util/stream/LongStream` | ` https://developer.android.com/reference/java/util/stream/Stream#mapMultiToLong(java.util.function.BiConsumer<?%20super%20T,?%20super%20java.util.function.LongConsumer>)(https://developer.android.com/reference/java/util/function/BiConsumer<? super T, ? super https://developer.android.com/reference/java/util/function/LongConsumer> mapper) ` Returns a `LongStream` consisting of the results of replacing each element of this stream with multiple elements, specifically zero or more elements. |
| ` abstract https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/Stream#mapToDouble(java.util.function.ToDoubleFunction<?%20super%20T>)(https://developer.android.com/reference/java/util/function/ToDoubleFunction<? super T> mapper) ` Returns a `DoubleStream` consisting of the results of applying the given function to the elements of this stream. |
| ` abstract https://developer.android.com/reference/java/util/stream/IntStream` | ` https://developer.android.com/reference/java/util/stream/Stream#mapToInt(java.util.function.ToIntFunction<?%20super%20T>)(https://developer.android.com/reference/java/util/function/ToIntFunction<? super T> mapper) ` Returns an `IntStream` consisting of the results of applying the given function to the elements of this stream. |
| ` abstract https://developer.android.com/reference/java/util/stream/LongStream` | ` https://developer.android.com/reference/java/util/stream/Stream#mapToLong(java.util.function.ToLongFunction<?%20super%20T>)(https://developer.android.com/reference/java/util/function/ToLongFunction<? super T> mapper) ` Returns a `LongStream` consisting of the results of applying the given function to the elements of this stream. |
| ` abstract https://developer.android.com/reference/java/util/Optional<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#max(java.util.Comparator<?%20super%20T>)(https://developer.android.com/reference/java/util/Comparator<? super T> comparator) ` Returns the maximum element of this stream according to the provided `Comparator`. |
| ` abstract https://developer.android.com/reference/java/util/Optional<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#min(java.util.Comparator<?%20super%20T>)(https://developer.android.com/reference/java/util/Comparator<? super T> comparator) ` Returns the minimum element of this stream according to the provided `Comparator`. |
| ` abstract boolean` | ` https://developer.android.com/reference/java/util/stream/Stream#noneMatch(java.util.function.Predicate<?%20super%20T>)(https://developer.android.com/reference/java/util/function/Predicate<? super T> predicate) ` Returns whether no elements of this stream match the provided predicate. |
| ` static <T> https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#of(T)(T t) ` Returns a sequential `Stream` containing a single element. |
| ` static <T> https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#of(T[])(T... values) ` Returns a sequential ordered stream whose elements are the specified values. |
| ` static <T> https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#ofNullable(T)(T t) ` Returns a sequential `Stream` containing a single element, if non-null, otherwise returns an empty `Stream`. |
| ` abstract https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#peek(java.util.function.Consumer<?%20super%20T>)(https://developer.android.com/reference/java/util/function/Consumer<? super T> 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. |
| ` abstract T` | ` https://developer.android.com/reference/java/util/stream/Stream#reduce(T,%20java.util.function.BinaryOperator<T>)(T identity, https://developer.android.com/reference/java/util/function/BinaryOperator<T> accumulator) ` Performs a [reduction](https://developer.android.com/reference/java/util/stream/package-summary#Reduction) on the elements of this stream, using the provided identity value and an [associative](https://developer.android.com/reference/java/util/stream/package-summary#Associativity) accumulation function, and returns the reduced value. |
| ` abstract <U> U` | ` https://developer.android.com/reference/java/util/stream/Stream#reduce(U,%20java.util.function.BiFunction<U,?%20super%20T,U>,%20java.util.function.BinaryOperator<U>)(U identity, https://developer.android.com/reference/java/util/function/BiFunction<U, ? super T, U> accumulator, https://developer.android.com/reference/java/util/function/BinaryOperator<U> combiner) ` Performs a [reduction](https://developer.android.com/reference/java/util/stream/package-summary#Reduction) on the elements of this stream, using the provided identity, accumulation and combining functions. |
| ` abstract https://developer.android.com/reference/java/util/Optional<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#reduce(java.util.function.BinaryOperator<T>)(https://developer.android.com/reference/java/util/function/BinaryOperator<T> accumulator) ` Performs a [reduction](https://developer.android.com/reference/java/util/stream/package-summary#Reduction) on the elements of this stream, using an [associative](https://developer.android.com/reference/java/util/stream/package-summary#Associativity) accumulation function, and returns an `Optional` describing the reduced value, if any. |
| ` abstract https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#skip(long)(long n) ` Returns a stream consisting of the remaining elements of this stream after discarding the first `n` elements of the stream. |
| ` abstract https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#sorted(java.util.Comparator<?%20super%20T>)(https://developer.android.com/reference/java/util/Comparator<? super T> comparator) ` Returns a stream consisting of the elements of this stream, sorted according to the provided `Comparator`. |
| ` abstract https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#sorted()() ` Returns a stream consisting of the elements of this stream, sorted according to natural order. |
| ` default https://developer.android.com/reference/java/util/stream/Stream<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#takeWhile(java.util.function.Predicate<?%20super%20T>)(https://developer.android.com/reference/java/util/function/Predicate<? super T> 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. |
| ` abstract https://developer.android.com/reference/java/lang/Object` | ` https://developer.android.com/reference/java/util/stream/Stream#toArray()() ` Returns an array containing the elements of this stream. |
| ` abstract <A> A[]` | ` https://developer.android.com/reference/java/util/stream/Stream#toArray(java.util.function.IntFunction<A[]>)(https://developer.android.com/reference/java/util/function/IntFunction<A[]> generator) ` Returns an array containing the elements of this stream, using the provided `generator` function to allocate the returned array, as well as any additional arrays that might be required for a partitioned execution or for resizing. |
| ` default https://developer.android.com/reference/java/util/List<T>` | ` https://developer.android.com/reference/java/util/stream/Stream#toList()() ` Accumulates the elements of this stream into a `List`. |

| ### Inherited methods |
|---|---|
| From interface ` https://developer.android.com/reference/java/util/stream/BaseStream ` |---|---| | ` abstract void` | ` https://developer.android.com/reference/java/util/stream/BaseStream#close()() ` Closes this stream, causing all close handlers for this stream pipeline to be called. | | ` abstract boolean` | ` https://developer.android.com/reference/java/util/stream/BaseStream#isParallel()() ` Returns whether this stream, if a terminal operation were to be executed, would execute in parallel. | | ` abstract https://developer.android.com/reference/java/util/Iterator<T>` | ` https://developer.android.com/reference/java/util/stream/BaseStream#iterator()() ` Returns an iterator for the elements of this stream. | | ` abstract S` | ` https://developer.android.com/reference/java/util/stream/BaseStream#onClose(java.lang.Runnable)(https://developer.android.com/reference/java/lang/Runnable closeHandler) ` Returns an equivalent stream with an additional close handler. | | ` abstract S` | ` https://developer.android.com/reference/java/util/stream/BaseStream#parallel()() ` Returns an equivalent stream that is parallel. | | ` abstract S` | ` https://developer.android.com/reference/java/util/stream/BaseStream#sequential()() ` Returns an equivalent stream that is sequential. | | ` abstract https://developer.android.com/reference/java/util/Spliterator<T>` | ` https://developer.android.com/reference/java/util/stream/BaseStream#spliterator()() ` Returns a spliterator for the elements of this stream. | | ` abstract S` | ` https://developer.android.com/reference/java/util/stream/BaseStream#unordered()() ` Returns an equivalent stream that is [unordered](https://developer.android.com/reference/java/util/stream/package-summary#Ordering). | ||
| From interface ` https://developer.android.com/reference/java/lang/AutoCloseable ` |---|---| | ` abstract void` | ` https://developer.android.com/reference/java/lang/AutoCloseable#close()() ` Closes this resource, relinquishing any underlying resources. | ||

## Public methods

### allMatch

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract boolean allMatch (Predicate<? super T> 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### 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` | `Predicate`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) predicate to apply to elements of this stream <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if either all elements of the stream match the provided predicate or the stream is empty, otherwise `false` <br /> |

### anyMatch

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract boolean anyMatch (Predicate<? super T> 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### API Note:

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

| Parameters ||
|---|---|
| `predicate` | `Predicate`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) predicate to apply to elements of this stream <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if any elements of the stream match the provided predicate, otherwise `false` <br /> |

### builder

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public static Builder<T> builder ()
```

Returns a builder for a `Stream`.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream.Builder<T>` | a stream builder <br /> |

### collect

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract R collect (Supplier<R> supplier, 
                BiConsumer<R, ? super T> accumulator, 
                BiConsumer<R, R> combiner)
```

Performs a [mutable
reduction](https://developer.android.com/reference/java/util/stream/package-summary#MutableReduction) 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 (T element : this stream)
            accumulator.accept(result, element);
        return result;

Like `https://developer.android.com/reference/java/util/stream/Stream#reduce(T,%20java.util.function.BinaryOperator<T>)`, `collect` operations
can be parallelized without requiring additional synchronization.

This is a [terminal
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### API Note:

- There are many existing classes in the JDK whose signatures are well-suited for use with method references as arguments to `collect()`. For example, the following will accumulate strings into an `ArrayList`:

      List<String> asList = stringStream.collect(ArrayList::new, ArrayList::add,
                                                     ArrayList::addAll);

  The following will take a stream of strings and concatenates them into a
  single string:

      String concat = stringStream.collect(StringBuilder::new, StringBuilder::append,
                                               StringBuilder::append)
                                      .toString();

| Parameters ||
|---|---|
| `supplier` | `Supplier`: 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. <br /> |
| `accumulator` | `BiConsumer`: an [associative](https://developer.android.com/reference/java/util/stream/package-summary#Associativity), [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function that must fold an element into a result container. <br /> |
| `combiner` | `BiConsumer`: an [associative](https://developer.android.com/reference/java/util/stream/package-summary#Associativity), [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) 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. <br /> |

| Returns ||
|---|---|
| `R` | the result of the reduction <br /> |

### collect

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract R collect (Collector<? super T, A, R> collector)
```

Performs a [mutable
reduction](https://developer.android.com/reference/java/util/stream/package-summary#MutableReduction) operation on the elements of this stream using a
`Collector`. A `Collector`
encapsulates the functions used as arguments to
`https://developer.android.com/reference/java/util/stream/Stream#collect(java.util.function.Supplier<R>,%20java.util.function.BiConsumer<R,?%20super%20T>,%20java.util.function.BiConsumer<R,R>)`, allowing for reuse of
collection strategies and composition of collect operations such as
multiple-level grouping or partitioning.

If the stream is parallel, and the `Collector`
is `https://developer.android.com/reference/java/util/stream/Collector.Characteristics#CONCURRENT`, and
either the stream is unordered or the collector is
`https://developer.android.com/reference/java/util/stream/Collector.Characteristics#UNORDERED`,
then a concurrent reduction will be performed (see `https://developer.android.com/reference/java/util/stream/Collector` for
details on concurrent reduction.)

This is a [terminal
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

When executed in parallel, multiple intermediate results may be
instantiated, populated, and merged so as to maintain isolation of
mutable data structures. Therefore, even when executed in parallel
with non-thread-safe data structures (such as `ArrayList`), no
additional synchronization is needed for a parallel reduction.

<br />

##### API Note:

- The following will accumulate strings into a List:

      List<String> asList = stringStream.collect(Collectors.toList());

  The following will classify `Person` objects by city:

      Map<String, List<Person>> peopleByCity
              = personStream.collect(Collectors.groupingBy(Person::getCity));

  The following will classify `Person` objects by state and city,
  cascading two `Collector`s together:

      Map<String, Map<String, List<Person>>> peopleByStateAndCity
              = personStream.collect(Collectors.groupingBy(Person::getState,
                                                           Collectors.groupingBy(Person::getCity)));

| Parameters ||
|---|---|
| `collector` | `Collector`: the `Collector` describing the reduction <br /> |

| Returns ||
|---|---|
| `R` | the result of the reduction <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream#collect(java.util.function.Supplier<R>,%20java.util.function.BiConsumer<R,?%20super%20T>,%20java.util.function.BiConsumer<R,R>)`
- `https://developer.android.com/reference/java/util/stream/Collectors`

### concat

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public static Stream<T> concat (Stream<? extends T> a, 
                Stream<? extends T> 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.

<br />

##### 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:

      Stream<T> concat = Stream.of(s1, s2, s3, s4).flatMap(s -> s);

##### 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`.

  Subsequent changes to the sequential/parallel execution mode of the
  returned stream are not guaranteed to be propagated to the input streams.

| Parameters ||
|---|---|
| `a` | `Stream`: the first stream <br /> |
| `b` | `Stream`: the second stream <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | the concatenation of the two input streams <br /> |

### count

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract long count ()
```

Returns the count of elements in this stream. This is a special case of
a [reduction](https://developer.android.com/reference/java/util/stream/package-summary#Reduction) and is
equivalent to:

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

This is a [terminal operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### 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:

      List<String> l = Arrays.asList("A", "B", "C", "D");
          long count = l.stream().peek(System.out::println).count();

  The number of elements covered by the stream source, a `List`, 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 the size of the `List` and there is no need to execute the pipeline and, as a side-effect, print out the list elements.

| Returns ||
|---|---|
| `long` | the count of elements in this stream <br /> |

### distinct

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Stream<T> distinct ()
```

Returns a stream consisting of the distinct elements (according to
`https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object)`) of this stream.

For ordered streams, the selection of distinct elements is stable
(for duplicated elements, the element appearing first in the encounter
order is preserved.) For unordered streams, no stability guarantees
are made.

This is a [stateful
intermediate operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### API Note:

- Preserving stability for `distinct()` in parallel pipelines is relatively expensive (requires that the operation act as a full barrier, with substantial buffering overhead), and stability is often not needed. Using an unordered stream source (such as `https://developer.android.com/reference/java/util/stream/Stream#generate(java.util.function.Supplier<?%20extends%20T>)`) or removing the ordering constraint with `https://developer.android.com/reference/java/util/stream/BaseStream#unordered()` may result in significantly more efficient execution for `distinct()` 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 `distinct()` in parallel pipelines, switching to sequential execution with `https://developer.android.com/reference/java/util/stream/BaseStream#sequential()` may improve performance.

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | the new stream <br /> |

### dropWhile

Added in [API level 34](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public Stream<T> dropWhile (Predicate<? super T> 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### 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 `https://developer.android.com/reference/java/util/stream/Stream#generate(java.util.function.Supplier<?%20extends%20T>)`) or removing the ordering constraint with `https://developer.android.com/reference/java/util/stream/BaseStream#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 `https://developer.android.com/reference/java/util/stream/BaseStream#sequential()` may improve performance.

##### Implementation Requirements:

- The default implementation obtains the `https://developer.android.com/reference/java/util/stream/BaseStream#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 `https://developer.android.com/reference/java/util/stream/BaseStream#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.

| Parameters ||
|---|---|
| `predicate` | `Predicate`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) predicate to apply to elements to determine the longest prefix of elements. <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | the new stream <br /> |

### empty

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public static Stream<T> empty ()
```

Returns an empty sequential `Stream`.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | an empty sequential stream <br /> |

### filter

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Stream<T> filter (Predicate<? super T> predicate)
```

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

This is an [intermediate
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `predicate` | `Predicate`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) predicate to apply to each element to determine if it should be included <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | the new stream <br /> |

### findAny

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Optional<T> findAny ()
```

Returns an `https://developer.android.com/reference/java/util/Optional` describing some element of the stream, or an
empty `Optional` if the stream is empty.

This is a [short-circuiting
terminal operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

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 `https://developer.android.com/reference/java/util/stream/Stream#findFirst()` instead.)

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Optional<T>` | an `Optional` describing some element of this stream, or an empty `Optional` if the stream is empty <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the element selected is null |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream#findFirst()`

### findFirst

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Optional<T> findFirst ()
```

Returns an `https://developer.android.com/reference/java/util/Optional` describing the first element of this stream,
or an empty `Optional` 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Optional<T>` | an `Optional` describing the first element of this stream, or an empty `Optional` if the stream is empty <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the element selected is null |

### flatMap

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Stream<R> flatMap (Function<? super T, ? extends Stream<? extends R>> 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
`https://developer.android.com/reference/java/util/stream/BaseStream#close()` 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### API Note:

- The `flatMap()` operation has the effect of applying a one-to-many transformation to the elements of the stream, and then flattening the resulting elements into a new stream.

  **Examples.**

  If `orders` is a stream of purchase orders, and each purchase
  order contains a collection of line items, then the following produces a
  stream containing all the line items in all the orders:

      orders.flatMap(order -> order.getLineItems().stream())...

  If `path` is the path to a file, then the following produces a
  stream of the `words` contained in that file:

      Stream<String> lines = Files.lines(path, StandardCharsets.UTF_8);
          Stream<String> words = lines.flatMap(line -> Stream.of(line.split(" +")));

  The `mapper` function passed to `flatMap` splits a line, using a simple regular expression, into an array of words, and then creates a stream of words from that array.

| Parameters ||
|---|---|
| `mapper` | `Function`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function to apply to each element which produces a stream of new values <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<R>` | the new stream <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream#mapMulti(java.util.function.BiConsumer<?%20super%20T,?%20super%20java.util.function.Consumer<R>>)`

### flatMapToDouble

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract DoubleStream flatMapToDouble (Function<? super T, ? extends DoubleStream> mapper)
```

Returns an `DoubleStream` 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 `https://developer.android.com/reference/java/util/stream/BaseStream#close()` after its
contents have placed been into this stream. (If a mapped stream is
`null` an empty stream is used, instead.)

This is an [intermediate
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `mapper` | `Function`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function to apply to each element which produces a stream of new values <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/DoubleStream` | the new stream <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream#flatMap(java.util.function.Function<?%20super%20T,?%20extends%20java.util.stream.Stream<?%20extends%20R>>)`

### flatMapToInt

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract IntStream flatMapToInt (Function<? super T, ? extends IntStream> mapper)
```

Returns an `IntStream` 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 `https://developer.android.com/reference/java/util/stream/BaseStream#close()` 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `mapper` | `Function`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function to apply to each element which produces a stream of new values <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/IntStream` | the new stream <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream#flatMap(java.util.function.Function<?%20super%20T,?%20extends%20java.util.stream.Stream<?%20extends%20R>>)`

### flatMapToLong

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract LongStream flatMapToLong (Function<? super T, ? extends LongStream> mapper)
```

Returns an `LongStream` 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 `https://developer.android.com/reference/java/util/stream/BaseStream#close()` 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `mapper` | `Function`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function to apply to each element which produces a stream of new values <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/LongStream` | the new stream <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream#flatMap(java.util.function.Function<?%20super%20T,?%20extends%20java.util.stream.Stream<?%20extends%20R>>)`

### forEach

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract void forEach (Consumer<? super T> action)
```

Performs an action for each element of this stream.

This is a [terminal
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

The behavior of this operation is explicitly nondeterministic.
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.

<br />

| Parameters ||
|---|---|
| `action` | `Consumer`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference) action to perform on the elements <br /> |

### forEachOrdered

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract void forEachOrdered (Consumer<? super T> action)
```

Performs an action for each element of this stream, in the encounter
order of the stream if the stream has a defined encounter order.

This is a [terminal
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

This operation processes the elements one at a time, in encounter
order if one exists. Performing the action for one element
[*happens-before*](https://developer.android.com/reference/java/util/concurrent/package-summary.html#MemoryVisibility)
performing the action for subsequent elements, but for any given element,
the action may be performed in whatever thread the library chooses.

<br />

| Parameters ||
|---|---|
| `action` | `Consumer`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference) action to perform on the elements <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream#forEach(java.util.function.Consumer<?%20super%20T>)`

### gather

Added in [version 36.1](https://developer.android.com/topic/libraries/support-library/revisions)

```
public Stream<R> gather (Gatherer<? super T, ?, R> gatherer)
```

Returns a stream consisting of the results of applying the given
`https://developer.android.com/reference/java/util/stream/Gatherer` to the elements of this stream.

This is a [stateful
intermediate operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps) that is an
[extension point](https://developer.android.com/reference/java/util/stream/package-summary#Extensibility).

Gatherers are highly flexible and can describe a vast array of
possibly stateful operations, with support for short-circuiting, and
parallelization.

When executed in parallel, multiple intermediate results may be
instantiated, populated, and merged so as to maintain isolation of
mutable data structures. Therefore, even when executed in parallel
with non-thread-safe data structures (such as `ArrayList`), no
additional synchronization is needed for a parallel reduction.

Implementations are allowed, but not required, to detect consecutive
invocations and compose them into a single, fused, operation. This would
make the first expression below behave like the second:

    var stream1 = Stream.of(...).gather(gatherer1).gather(gatherer2);
        var stream2 = Stream.of(...).gather(gatherer1.andThen(gatherer2));

<br />

<br />

##### Implementation Requirements:

- The default implementation obtains the `https://developer.android.com/reference/java/util/stream/BaseStream#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 `https://developer.android.com/reference/java/util/stream/BaseStream#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. Implementations of this interface should provide their own implementation of this method.

| Parameters ||
|---|---|
| `gatherer` | `Gatherer`: a gatherer <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<R>` | the new stream <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Gatherers`

### generate

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public static Stream<T> generate (Supplier<? extends T> s)
```

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

<br />

| Parameters ||
|---|---|
| `s` | `Supplier`: the `Supplier` of generated elements <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | a new infinite sequential unordered `Stream` <br /> |

### iterate

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public static Stream<T> iterate (T seed, 
                UnaryOperator<T> f)
```

Returns an infinite sequential ordered `Stream` 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 `Stream` 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*](https://developer.android.com/reference/java/util/concurrent/package-summary.html#MemoryVisibility)
the action of applying `f` for subsequent elements. For any given
element the action may be performed in whatever thread the library
chooses.

<br />

| Parameters ||
|---|---|
| `seed` | `T`: the initial element <br /> |
| `f` | `UnaryOperator`: a function to be applied to the previous element to produce a new element <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | a new sequential `Stream` <br /> |

### iterate

Added in [API level 34](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public static Stream<T> iterate (T seed, 
                Predicate<? super T> hasNext, 
                UnaryOperator<T> next)
```

Returns a sequential ordered `Stream` 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.

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

    for (T index=seed; hasNext.test(index); index = next.apply(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*](https://developer.android.com/reference/java/util/concurrent/package-summary.html#MemoryVisibility)
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.

<br />

| Parameters ||
|---|---|
| `seed` | `T`: the initial element <br /> |
| `hasNext` | `Predicate`: a predicate to apply to elements to determine when the stream must terminate. <br /> |
| `next` | `UnaryOperator`: a function to be applied to the previous element to produce a new element <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | a new sequential `Stream` <br /> |

### limit

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Stream<T> 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### 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 `https://developer.android.com/reference/java/util/stream/Stream#generate(java.util.function.Supplier<?%20extends%20T>)`) or removing the ordering constraint with `https://developer.android.com/reference/java/util/stream/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 `https://developer.android.com/reference/java/util/stream/BaseStream#sequential()` may improve performance.

| Parameters ||
|---|---|
| `maxSize` | `long`: the number of elements the stream should be limited to <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | the new stream <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalArgumentException` | if `maxSize` is negative |

### map

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Stream<R> map (Function<? super T, ? extends R> mapper)
```

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

This is an [intermediate
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `mapper` | `Function`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function to apply to each element <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<R>` | the new stream <br /> |

### mapMulti

Added in [API level 34](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public Stream<R> mapMulti (BiConsumer<? super T, ? super Consumer<R>> 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](https://developer.android.com/reference/java/util/function/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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

If the [consumer](https://developer.android.com/reference/java/util/function/Consumer) argument is used outside the scope of
its application to the mapping function, the results are undefined.

<br />

##### API Note:

- This method is similar to `https://developer.android.com/reference/java/util/stream/Stream#flatMap(java.util.function.Function<?%20super%20T,?%20extends%20java.util.stream.Stream<?%20extends%20R>>)` in that it applies a one-to-many transformation to the elements of the stream and flattens the result elements into a new stream. This method is preferable to `flatMap` in the following circumstances:
  - When replacing each stream element with a small (possibly zero) number of elements. Using this method avoids the overhead of creating a new Stream instance for every group of result elements, as required by `flatMap`.
  - When it is easier to use an imperative approach for generating result elements than it is to return them in the form of a Stream.

  If a lambda expression is provided as the mapper function argument, additional type
  information may be necessary for proper inference of the element type `<R>` of
  the returned stream. This can be provided in the form of explicit type declarations for
  the lambda parameters or as an explicit type argument to the `mapMulti` call.

  **Examples**

  Given a stream of `Number` objects, the following
  produces a list containing only the `Integer` objects:

      Stream<Number> numbers = ... ;
          List<Integer> integers = numbers.<Integer>mapMulti((number, consumer) -> {
                  if (number instanceof Integer i)
                      consumer.accept(i);
              })
              .collect(Collectors.toList());

  If we have an `Iterable<Object>` and need to recursively expand its elements
  that are themselves of type `Iterable`, we can use `mapMulti` as follows:

      class C {
          static void expandIterable(Object e, Consumer<Object> c) {
              if (e instanceof Iterable<?> elements) {
                  for (Object ie : elements) {
                      expandIterable(ie, c);
                  }
              } else if (e != null) {
                  c.accept(e);
              }
          }

          public static void main(String[] args) {
              var nestedList = List.of(1, List.of(2, List.of(3, 4)), 5);
              Stream<Object> expandedStream = nestedList.stream().mapMulti(C::expandIterable);
          }
      }

##### Implementation Requirements:

- The default implementation invokes `https://developer.android.com/reference/java/util/stream/Stream#flatMap(java.util.function.Function<?%20super%20T,?%20extends%20java.util.stream.Stream<?%20extends%20R>>)` on this stream, passing a function that behaves as follows. First, it calls the mapper function with a `Consumer` that accumulates replacement elements into a newly created internal buffer. When the mapper function returns, it creates a stream from the internal buffer. Finally, it returns this stream to `flatMap`.

| Parameters ||
|---|---|
| `mapper` | `BiConsumer`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function that generates replacement elements <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<R>` | the new stream <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream#flatMap(java.util.function.Function<?%20super%20T,?%20extends%20java.util.stream.Stream<?%20extends%20R>>)`

### mapMultiToDouble

Added in [API level 34](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public DoubleStream mapMultiToDouble (BiConsumer<? super T, ? super DoubleConsumer> mapper)
```

Returns a `DoubleStream` 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](https://developer.android.com/reference/java/util/function/DoubleConsumer) 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

If the [consumer](https://developer.android.com/reference/java/util/function/DoubleConsumer) argument is used outside the scope of
its application to the mapping function, the results are undefined.

<br />

##### Implementation Requirements:

- The default implementation invokes `https://developer.android.com/reference/java/util/stream/Stream#flatMapToDouble(java.util.function.Function<?%20super%20T,?%20extends%20java.util.stream.DoubleStream>)` on this stream, passing a function that behaves as follows. First, it calls the mapper function with an `DoubleConsumer` that accumulates replacement elements into a newly created internal buffer. When the mapper function returns, it creates a `DoubleStream` from the internal buffer. Finally, it returns this stream to `flatMapToDouble`.

| Parameters ||
|---|---|
| `mapper` | `BiConsumer`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function that generates replacement elements <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/DoubleStream` | the new stream <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream#mapMulti(java.util.function.BiConsumer<?%20super%20T,?%20super%20java.util.function.Consumer<R>>)`

### mapMultiToInt

Added in [API level 34](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public IntStream mapMultiToInt (BiConsumer<? super T, ? super IntConsumer> mapper)
```

Returns an `IntStream` 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](https://developer.android.com/reference/java/util/function/IntConsumer) 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

If the [consumer](https://developer.android.com/reference/java/util/function/IntConsumer) argument is used outside the scope of
its application to the mapping function, the results are undefined.

<br />

##### Implementation Requirements:

- The default implementation invokes `https://developer.android.com/reference/java/util/stream/Stream#flatMapToInt(java.util.function.Function<?%20super%20T,?%20extends%20java.util.stream.IntStream>)` on this stream, passing a function that behaves as follows. First, it calls the mapper function with an `IntConsumer` that accumulates replacement elements into a newly created internal buffer. When the mapper function returns, it creates an `IntStream` from the internal buffer. Finally, it returns this stream to `flatMapToInt`.

| Parameters ||
|---|---|
| `mapper` | `BiConsumer`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function that generates replacement elements <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/IntStream` | the new stream <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream#mapMulti(java.util.function.BiConsumer<?%20super%20T,?%20super%20java.util.function.Consumer<R>>)`

### mapMultiToLong

Added in [API level 34](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public LongStream mapMultiToLong (BiConsumer<? super T, ? super LongConsumer> mapper)
```

Returns a `LongStream` 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](https://developer.android.com/reference/java/util/function/LongConsumer) 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

If the [consumer](https://developer.android.com/reference/java/util/function/LongConsumer) argument is used outside the scope of
its application to the mapping function, the results are undefined.

<br />

##### Implementation Requirements:

- The default implementation invokes `https://developer.android.com/reference/java/util/stream/Stream#flatMapToLong(java.util.function.Function<?%20super%20T,?%20extends%20java.util.stream.LongStream>)` 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 `flatMapToLong`.

| Parameters ||
|---|---|
| `mapper` | `BiConsumer`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function that generates replacement elements <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/LongStream` | the new stream <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream#mapMulti(java.util.function.BiConsumer<?%20super%20T,?%20super%20java.util.function.Consumer<R>>)`

### mapToDouble

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract DoubleStream mapToDouble (ToDoubleFunction<? super T> mapper)
```

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

This is an [intermediate
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `mapper` | `ToDoubleFunction`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function to apply to each element <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/DoubleStream` | the new stream <br /> |

### mapToInt

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract IntStream mapToInt (ToIntFunction<? super T> mapper)
```

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

This is an [intermediate operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `mapper` | `ToIntFunction`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function to apply to each element <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/IntStream` | the new stream <br /> |

### mapToLong

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract LongStream mapToLong (ToLongFunction<? super T> mapper)
```

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

This is an [intermediate
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `mapper` | `ToLongFunction`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function to apply to each element <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/LongStream` | the new stream <br /> |

### max

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Optional<T> max (Comparator<? super T> comparator)
```

Returns the maximum element of this stream according to the provided
`Comparator`. This is a special case of a
[reduction](https://developer.android.com/reference/java/util/stream/package-summary#Reduction).

This is a [terminal
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `comparator` | `Comparator`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) `Comparator` to compare elements of this stream <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Optional<T>` | an `Optional` describing the maximum element of this stream, or an empty `Optional` if the stream is empty <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the maximum element is null |

### min

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Optional<T> min (Comparator<? super T> comparator)
```

Returns the minimum element of this stream according to the provided
`Comparator`. This is a special case of a
[reduction](https://developer.android.com/reference/java/util/stream/package-summary#Reduction).

This is a [terminal operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `comparator` | `Comparator`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) `Comparator` to compare elements of this stream <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Optional<T>` | an `Optional` describing the minimum element of this stream, or an empty `Optional` if the stream is empty <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the minimum element is null |

### noneMatch

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract boolean noneMatch (Predicate<? super T> 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### 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` | `Predicate`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) predicate to apply to elements of this stream <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if either no elements of the stream match the provided predicate or the stream is empty, otherwise `false` <br /> |

### of

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public static Stream<T> of (T t)
```

Returns a sequential `Stream` containing a single element.

<br />

| Parameters ||
|---|---|
| `t` | `T`: the single element <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | a singleton sequential stream <br /> |

### of

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public static Stream<T> of (T... values)
```

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

<br />

| Parameters ||
|---|---|
| `values` | `T`: the elements of the new stream <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | the new stream <br /> |

### ofNullable

Added in [API level 34](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public static Stream<T> ofNullable (T t)
```

Returns a sequential `Stream` containing a single element, if
non-null, otherwise returns an empty `Stream`.

<br />

| Parameters ||
|---|---|
| `t` | `T`: the single element <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | a stream with a single element if the specified element is non-null, otherwise an empty stream <br /> |

### peek

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Stream<T> peek (Consumer<? super T> 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

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.

<br />

##### 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:

      Stream.of("one", "two", "three", "four")
              .filter(e -> e.length() > 3)
              .peek(e -> System.out.println("Filtered value: " + e))
              .map(String::toUpperCase)
              .peek(e -> System.out.println("Mapped value: " + e))
              .collect(Collectors.toList());

  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
  `https://developer.android.com/reference/java/util/stream/Stream#count()`), the action will not be invoked for those elements.

| Parameters ||
|---|---|
| `action` | `Consumer`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference) action to perform on the elements as they are consumed from the stream <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | the new stream <br /> |

### reduce

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract T reduce (T identity, 
                BinaryOperator<T> accumulator)
```

Performs a [reduction](https://developer.android.com/reference/java/util/stream/package-summary#Reduction) on the
elements of this stream, using the provided identity value and an
[associative](https://developer.android.com/reference/java/util/stream/package-summary#Associativity)
accumulation function, and returns the reduced value. This is equivalent
to:

    T result = identity;
        for (T element : this stream)
            result = accumulator.apply(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 `t`,
`accumulator.apply(identity, t)` is equal to `t`.
The `accumulator` function must be an
[associative](https://developer.android.com/reference/java/util/stream/package-summary#Associativity) function.

This is a [terminal
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### API Note:

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

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

  or:

      Integer 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.

| Parameters ||
|---|---|
| `identity` | `T`: the identity value for the accumulating function <br /> |
| `accumulator` | `BinaryOperator`: an [associative](https://developer.android.com/reference/java/util/stream/package-summary#Associativity), [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function for combining two values <br /> |

| Returns ||
|---|---|
| `T` | the result of the reduction <br /> |

### reduce

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract U reduce (U identity, 
                BiFunction<U, ? super T, U> accumulator, 
                BinaryOperator<U> combiner)
```

Performs a [reduction](https://developer.android.com/reference/java/util/stream/package-summary#Reduction) on the
elements of this stream, using the provided identity, accumulation and
combining functions. This is equivalent to:

    U result = identity;
        for (T element : this stream)
            result = accumulator.apply(result, element)
        return result;

but is not constrained to execute sequentially.

The `identity` value must be an identity for the combiner
function. This means that for all `u`, `combiner(identity, u)`
is equal to `u`. Additionally, the `combiner` function
must be compatible with the `accumulator` function; for all
`u` and `t`, the following must hold:

    combiner.apply(u, accumulator.apply(identity, t)) == accumulator.apply(u, t)

This is a [terminal
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### API Note:

- Many reductions using this form can be represented more simply by an explicit combination of `map` and `reduce` operations. The `accumulator` function acts as a fused mapper and accumulator, which can sometimes be more efficient than separate mapping and reduction, such as when knowing the previously reduced value allows you to avoid some computation.

| Parameters ||
|---|---|
| `identity` | `U`: the identity value for the combiner function <br /> |
| `accumulator` | `BiFunction`: an [associative](https://developer.android.com/reference/java/util/stream/package-summary#Associativity), [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function for incorporating an additional element into a result <br /> |
| `combiner` | `BinaryOperator`: an [associative](https://developer.android.com/reference/java/util/stream/package-summary#Associativity), [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function for combining two values, which must be compatible with the accumulator function <br /> |

| Returns ||
|---|---|
| `U` | the result of the reduction <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream#reduce(java.util.function.BinaryOperator<T>)`
- `https://developer.android.com/reference/java/util/stream/Stream#reduce(T,%20java.util.function.BinaryOperator<T>)`

### reduce

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Optional<T> reduce (BinaryOperator<T> accumulator)
```

Performs a [reduction](https://developer.android.com/reference/java/util/stream/package-summary#Reduction) on the
elements of this stream, using an
[associative](https://developer.android.com/reference/java/util/stream/package-summary#Associativity) accumulation
function, and returns an `Optional` describing the reduced value,
if any. This is equivalent to:

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

but is not constrained to execute sequentially.

The `accumulator` function must be an
[associative](https://developer.android.com/reference/java/util/stream/package-summary#Associativity) function.

This is a [terminal
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `accumulator` | `BinaryOperator`: an [associative](https://developer.android.com/reference/java/util/stream/package-summary#Associativity), [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) function for combining two values <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Optional<T>` | an `https://developer.android.com/reference/java/util/Optional` describing the result of the reduction <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the result of the reduction is null |

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream#reduce(T,%20java.util.function.BinaryOperator<T>)`
- `https://developer.android.com/reference/java/util/stream/Stream#min(java.util.Comparator<?%20super%20T>)`
- `https://developer.android.com/reference/java/util/stream/Stream#max(java.util.Comparator<?%20super%20T>)`

### skip

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Stream<T> 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### 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 `https://developer.android.com/reference/java/util/stream/Stream#generate(java.util.function.Supplier<?%20extends%20T>)`) or removing the ordering constraint with `https://developer.android.com/reference/java/util/stream/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 `https://developer.android.com/reference/java/util/stream/BaseStream#sequential()` may improve performance.

| Parameters ||
|---|---|
| `n` | `long`: the number of leading elements to skip <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | the new stream <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalArgumentException` | if `n` is negative |

### sorted

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Stream<T> sorted (Comparator<? super T> comparator)
```

Returns a stream consisting of the elements of this stream, sorted
according to the provided `Comparator`.

For ordered streams, the sort is stable. For unordered streams, no
stability guarantees are made.

This is a [stateful
intermediate operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `comparator` | `Comparator`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) `Comparator` to be used to compare stream elements <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | the new stream <br /> |

### sorted

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Stream<T> sorted ()
```

Returns a stream consisting of the elements of this stream, sorted
according to natural order. If the elements of this stream are not
`Comparable`, a `java.lang.ClassCastException` may be thrown
when the terminal operation is executed.

For ordered streams, the sort is stable. For unordered streams, no
stability guarantees are made.

This is a [stateful
intermediate operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | the new stream <br /> |

### takeWhile

Added in [API level 34](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public Stream<T> takeWhile (Predicate<? super T> 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### 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 `https://developer.android.com/reference/java/util/stream/Stream#generate(java.util.function.Supplier<?%20extends%20T>)`) or removing the ordering constraint with `https://developer.android.com/reference/java/util/stream/BaseStream#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 `https://developer.android.com/reference/java/util/stream/BaseStream#sequential()` may improve performance.

##### Implementation Requirements:

- The default implementation obtains the `https://developer.android.com/reference/java/util/stream/BaseStream#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 `https://developer.android.com/reference/java/util/stream/BaseStream#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.

| Parameters ||
|---|---|
| `predicate` | `Predicate`: a [non-interfering](https://developer.android.com/reference/java/util/stream/package-summary#NonInterference), [stateless](https://developer.android.com/reference/java/util/stream/package-summary#Statelessness) predicate to apply to elements to determine the longest prefix of elements. <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<T>` | the new stream <br /> |

### toArray

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Object[] toArray ()
```

Returns an array containing the elements of this stream.

This is a [terminal
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Object` | an array, whose [runtime component type](https://developer.android.com/reference/java/lang/Class#getComponentType()) is `Object`, containing the elements of this stream <br /> |

### toArray

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract A[] toArray (IntFunction<A[]> generator)
```

Returns an array containing the elements of this stream, using the
provided `generator` function to allocate the returned array, as
well as any additional arrays that might be required for a partitioned
execution or for resizing.

This is a [terminal
operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### API Note:

- The generator function takes an integer, which is the size of the desired array, and produces an array of the desired size. This can be concisely expressed with an array constructor reference:

      Person[] men = people.stream()
                               .filter(p -> p.getGender() == MALE)
                               .toArray(Person[]::new);

| Parameters ||
|---|---|
| `generator` | `IntFunction`: a function which produces a new array of the desired type and the provided length <br /> |

| Returns ||
|---|---|
| `A[]` | an array containing the elements in this stream <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ArrayStoreException` | if the runtime type of any element of this stream is not assignable to the [runtime component type](https://developer.android.com/reference/java/lang/Class#getComponentType()) of the generated array |

### toList

Added in [API level 34](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public List<T> toList ()
```

Accumulates the elements of this stream into a `List`. The elements in
the list will be in this stream's encounter order, if one exists. The returned List
is unmodifiable; calls to any mutator method will always cause
`UnsupportedOperationException` to be thrown. There are no
guarantees on the implementation type or serializability of the returned List.

The returned instance may be [value-based](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/doc-files/ValueBased.html).
Callers should make no assumptions about the identity of the returned instances.
Identity-sensitive operations on these instances (reference equality (`==`),
identity hash code, and synchronization) are unreliable and should be avoided.

This is a [terminal operation](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

##### API Note:

- If more control over the returned object is required, use `https://developer.android.com/reference/java/util/stream/Collectors#toCollection(java.util.function.Supplier<C>)`.

##### Implementation Note:

- Most instances of Stream will override this method and provide an implementation that is highly optimized compared to the implementation in this interface.

##### Implementation Requirements:

- The implementation in this interface returns a List produced as if by the following:

      Collections.unmodifiableList(new ArrayList<>(Arrays.asList(this.toArray())))

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/List<T>` | a List containing the stream elements <br /> |