All Superinterfaces:

AutoCloseable, BaseStream<Double,DoubleStream>
```
public interface DoubleStream
extends BaseStream<Double,DoubleStream>
```
A sequence of primitive double-valued elements supporting sequential and parallel aggregate operations. This is the double primitive specialization of Stream.
The following example illustrates an aggregate operation using Stream and DoubleStream, computing the sum of the weights of the red widgets:
```
     double sum = widgets.stream()
                         .filter(w -> w.getColor() == RED)
                         .mapToDouble(w -> w.getWeight())
                         .sum();
 
```
See the class documentation for Stream and the package documentation for java.util.stream for additional specification of streams, stream operations, stream pipelines, and parallelism.
Since:

1.8

See Also:

Stream, java.util.stream

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static interface DoubleStream.Builder
A mutable builder for a DoubleStream.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method	Description
`boolean`	`allMatch(DoublePredicate predicate)`	Returns whether all elements of this stream match the provided predicate.
`boolean`	`anyMatch(DoublePredicate predicate)`	Returns whether any elements of this stream match the provided predicate.
`OptionalDouble`	`average()`	Returns an `OptionalDouble` describing the arithmetic mean of elements of this stream, or an empty optional if this stream is empty.
`Stream<Double>`	`boxed()`	Returns a `Stream` consisting of the elements of this stream, boxed to `Double`.
`static DoubleStream.Builder`	`builder()`	Returns a builder for a `DoubleStream`.
`<R> R`	`collect(Supplier<R> supplier, ObjDoubleConsumer<R> accumulator, BiConsumer<R,R> combiner)`	Performs a mutable reduction operation on the elements of this stream.
`static DoubleStream`	`concat(DoubleStream a, DoubleStream b)`	Creates a lazily concatenated stream whose elements are all the elements of the first stream followed by all the elements of the second stream.
`long`	`count()`	Returns the count of elements in this stream.
`DoubleStream`	`distinct()`	Returns a stream consisting of the distinct elements of this stream.
`default DoubleStream`	`dropWhile(DoublePredicate 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 DoubleStream`	`empty()`	Returns an empty sequential `DoubleStream`.
`DoubleStream`	`filter(DoublePredicate predicate)`	Returns a stream consisting of the elements of this stream that match the given predicate.
`OptionalDouble`	`findAny()`	Returns an `OptionalDouble` describing some element of the stream, or an empty `OptionalDouble` if the stream is empty.
`OptionalDouble`	`findFirst()`	Returns an `OptionalDouble` describing the first element of this stream, or an empty `OptionalDouble` if the stream is empty.
`DoubleStream`	`flatMap(DoubleFunction<? extends DoubleStream> mapper)`	Returns a stream consisting of the results of replacing each element of this stream with the contents of a mapped stream produced by applying the provided mapping function to each element.
`void`	`forEach(DoubleConsumer action)`	Performs an action for each element of this stream.
`void`	`forEachOrdered(DoubleConsumer action)`	Performs an action for each element of this stream, guaranteeing that each element is processed in encounter order for streams that have a defined encounter order.
`static DoubleStream`	`generate(DoubleSupplier s)`	Returns an infinite sequential unordered stream where each element is generated by the provided `DoubleSupplier`.
`static DoubleStream`	`iterate(double seed, DoublePredicate hasNext, DoubleUnaryOperator next)`	Returns a sequential ordered `DoubleStream` produced by iterative application of the given `next` function to an initial element, conditioned on satisfying the given `hasNext` predicate.
`static DoubleStream`	`iterate(double seed, DoubleUnaryOperator f)`	Returns an infinite sequential ordered `DoubleStream` produced by iterative application of a function `f` to an initial element `seed`, producing a `Stream` consisting of `seed`, `f(seed)`, `f(f(seed))`, etc.
`PrimitiveIterator.OfDouble`	`iterator()`	Returns an iterator for the elements of this stream.
`DoubleStream`	`limit(long maxSize)`	Returns a stream consisting of the elements of this stream, truncated to be no longer than `maxSize` in length.
`DoubleStream`	`map(DoubleUnaryOperator mapper)`	Returns a stream consisting of the results of applying the given function to the elements of this stream.
`IntStream`	`mapToInt(DoubleToIntFunction mapper)`	Returns an `IntStream` consisting of the results of applying the given function to the elements of this stream.
`LongStream`	`mapToLong(DoubleToLongFunction mapper)`	Returns a `LongStream` consisting of the results of applying the given function to the elements of this stream.
`<U> Stream<U>`	`mapToObj(DoubleFunction<? extends U> mapper)`	Returns an object-valued `Stream` consisting of the results of applying the given function to the elements of this stream.
`OptionalDouble`	`max()`	Returns an `OptionalDouble` describing the maximum element of this stream, or an empty OptionalDouble if this stream is empty.
`OptionalDouble`	`min()`	Returns an `OptionalDouble` describing the minimum element of this stream, or an empty OptionalDouble if this stream is empty.
`boolean`	`noneMatch(DoublePredicate predicate)`	Returns whether no elements of this stream match the provided predicate.
`static DoubleStream`	`of(double t)`	Returns a sequential `DoubleStream` containing a single element.
`static DoubleStream`	`of(double... values)`	Returns a sequential ordered stream whose elements are the specified values.
`DoubleStream`	`parallel()`	Returns an equivalent stream that is parallel.
`DoubleStream`	`peek(DoubleConsumer 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.
`double`	`reduce(double identity, DoubleBinaryOperator op)`	Performs a reduction on the elements of this stream, using the provided identity value and an associative accumulation function, and returns the reduced value.
`OptionalDouble`	`reduce(DoubleBinaryOperator op)`	Performs a reduction on the elements of this stream, using an associative accumulation function, and returns an `OptionalDouble` describing the reduced value, if any.
`DoubleStream`	`sequential()`	Returns an equivalent stream that is sequential.
`DoubleStream`	`skip(long n)`	Returns a stream consisting of the remaining elements of this stream after discarding the first `n` elements of the stream.
`DoubleStream`	`sorted()`	Returns a stream consisting of the elements of this stream in sorted order.
`Spliterator.OfDouble`	`spliterator()`	Returns a spliterator for the elements of this stream.
`double`	`sum()`	Returns the sum of elements in this stream.
`DoubleSummaryStatistics`	`summaryStatistics()`	Returns a `DoubleSummaryStatistics` describing various summary data about the elements of this stream.
`default DoubleStream`	`takeWhile(DoublePredicate 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.
`double[]`	`toArray()`	Returns an array containing the elements of this stream.

Methods inherited from interface java.util.stream.BaseStream
close, isParallel, onClose, unordered

- Method Detail
  - filter
```
DoubleStream filter(DoublePredicate predicate)
```
    Returns a stream consisting of the elements of this stream that match the given predicate.
    This is an intermediate operation.
    
    Parameters:
    
    predicate - a non-interfering, stateless predicate to apply to each element to determine if it should be included
    
    Returns:
    
    the new stream
  - map
```
DoubleStream map(DoubleUnaryOperator mapper)
```
    Returns a stream consisting of the results of applying the given function to the elements of this stream.
    This is an intermediate operation.
    
    Parameters:
    
    mapper - a non-interfering, stateless function to apply to each element
    
    Returns:
    
    the new stream
  - mapToObj
```
<U> Stream<U> mapToObj(DoubleFunction<? extends U> mapper)
```
    Returns an object-valued Stream consisting of the results of applying the given function to the elements of this stream.
    This is an intermediate operation.
    
    Type Parameters:
    
    U - the element type of the new stream
    
    Parameters:
    
    mapper - a non-interfering, stateless function to apply to each element
    
    Returns:
    
    the new stream
  - mapToInt
```
IntStream mapToInt(DoubleToIntFunction mapper)
```
    Returns an IntStream consisting of the results of applying the given function to the elements of this stream.
    This is an intermediate operation.
    
    Parameters:
    
    mapper - a non-interfering, stateless function to apply to each element
    
    Returns:
    
    the new stream
  - mapToLong
```
LongStream mapToLong(DoubleToLongFunction mapper)
```
    Returns a LongStream consisting of the results of applying the given function to the elements of this stream.
    This is an intermediate operation.
    
    Parameters:
    
    mapper - a non-interfering, stateless function to apply to each element
    
    Returns:
    
    the new stream
  - flatMap
```
DoubleStream flatMap(DoubleFunction<? extends DoubleStream> mapper)
```
    Returns a stream consisting of the results of replacing each element of this stream with the contents of a mapped stream produced by applying the provided mapping function to each element. Each mapped stream is closed after its contents have been placed into this stream. (If a mapped stream is null an empty stream is used, instead.)
    This is an intermediate operation.
    
    Parameters:
    
    mapper - a non-interfering, stateless function to apply to each element which produces a DoubleStream of new values
    
    Returns:
    
    the new stream
    
    See Also:
    
    Stream.flatMap(Function)
  - distinct
```
DoubleStream distinct()
```
    Returns a stream consisting of the distinct elements of this stream. The elements are compared for equality according to Double.compare(double, double).
    This is a stateful intermediate operation.
    
    Returns:
    
    the result stream
  - sorted
```
DoubleStream sorted()
```
    Returns a stream consisting of the elements of this stream in sorted order. The elements are compared for equality according to Double.compare(double, double).
    This is a stateful intermediate operation.
    
    Returns:
    
    the result stream
  - peek
```
DoubleStream peek(DoubleConsumer action)
```
    Returns a stream consisting of the elements of this stream, additionally performing the provided action on each element as elements are consumed from the resulting stream.
    This is an intermediate operation.
    For parallel stream pipelines, the action may be called at whatever time and in whatever thread the element is made available by the upstream operation. If the action modifies shared state, it is responsible for providing the required synchronization.
    API Note:
    
    This method exists mainly to support debugging, where you want to see the elements as they flow past a certain point in a pipeline:
    DoubleStream.of(1, 2, 3, 4) .filter(e -> e > 2) .peek(e -> System.out.println("Filtered value: " + e)) .map(e -> e * e) .peek(e -> System.out.println("Mapped value: " + e)) .sum();
    
    In cases where the stream implementation is able to optimize away the production of some or all the elements (such as with short-circuiting operations like findFirst, or in the example described in count()), the action will not be invoked for those elements.
    
    Parameters:
    
    action - a non-interfering action to perform on the elements as they are consumed from the stream
    
    Returns:
    
    the new stream
  - limit
```
DoubleStream limit(long maxSize)
```
    Returns a stream consisting of the elements of this stream, truncated to be no longer than maxSize in length.
    This is a short-circuiting stateful intermediate operation.
    
    API Note:
    
    While limit() is generally a cheap operation on sequential stream pipelines, it can be quite expensive on ordered parallel pipelines, especially for large values of maxSize, since limit(n) is constrained to return not just any n elements, but the first n elements in the encounter order. Using an unordered stream source (such as generate(DoubleSupplier)) or removing the ordering constraint with BaseStream.unordered() may result in significant speedups of limit() in parallel pipelines, if the semantics of your situation permit. If consistency with encounter order is required, and you are experiencing poor performance or memory utilization with limit() in parallel pipelines, switching to sequential execution with sequential() may improve performance.
    
    Parameters:
    
    maxSize - the number of elements the stream should be limited to
    
    Returns:
    
    the new stream
    
    Throws:
    
    IllegalArgumentException - if maxSize is negative
  - skip
```
DoubleStream skip(long n)
```
    Returns a stream consisting of the remaining elements of this stream after discarding the first n elements of the stream. If this stream contains fewer than n elements then an empty stream will be returned.
    This is a stateful intermediate operation.
    
    API Note:
    
    While skip() is generally a cheap operation on sequential stream pipelines, it can be quite expensive on ordered parallel pipelines, especially for large values of n, since skip(n) is constrained to skip not just any n elements, but the first n elements in the encounter order. Using an unordered stream source (such as generate(DoubleSupplier)) or removing the ordering constraint with BaseStream.unordered() may result in significant speedups of skip() in parallel pipelines, if the semantics of your situation permit. If consistency with encounter order is required, and you are experiencing poor performance or memory utilization with skip() in parallel pipelines, switching to sequential execution with sequential() may improve performance.
    
    Parameters:
    
    n - the number of leading elements to skip
    
    Returns:
    
    the new stream
    
    Throws:
    
    IllegalArgumentException - if n is negative
  - takeWhile
```
default DoubleStream takeWhile(DoublePredicate 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.
    
    API Note:
    
    While takeWhile() is generally a cheap operation on sequential stream pipelines, it can be quite expensive on ordered parallel pipelines, since the operation is constrained to return not just any valid prefix, but the longest prefix of elements in the encounter order. Using an unordered stream source (such as generate(DoubleSupplier)) or removing the ordering constraint with 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 sequential() may improve performance.
    
    Implementation Requirements:
    
    The default implementation obtains the spliterator of this stream, wraps that spliterator so as to support the semantics of this operation on traversal, and returns a new stream associated with the wrapped spliterator. The returned stream preserves the execution characteristics of this stream (namely parallel or sequential execution as per 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 - a non-interfering, stateless predicate to apply to elements to determine the longest prefix of elements.
    
    Returns:
    
    the new stream
    
    Since:
    
    9
  - dropWhile
```
default DoubleStream dropWhile(DoublePredicate 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.
    
    API Note:
    
    While dropWhile() is generally a cheap operation on sequential stream pipelines, it can be quite expensive on ordered parallel pipelines, since the operation is constrained to return not just any valid prefix, but the longest prefix of elements in the encounter order. Using an unordered stream source (such as generate(DoubleSupplier)) or removing the ordering constraint with 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 sequential() may improve performance.
    
    Implementation Requirements:
    
    The default implementation obtains the spliterator of this stream, wraps that spliterator so as to support the semantics of this operation on traversal, and returns a new stream associated with the wrapped spliterator. The returned stream preserves the execution characteristics of this stream (namely parallel or sequential execution as per 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 - a non-interfering,

Interface DoubleStream

Nested Class Summary

Method Summary

Methods inherited from interface java.util.stream.BaseStream

Method Detail

filter

map

mapToObj

mapToInt

mapToLong

flatMap

distinct

sorted

peek

limit

skip

takeWhile

dropWhile