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/DoubleStream#nestedclasses) \| [Methods](https://developer.android.com/reference/java/util/stream/DoubleStream#pubmethods) \| [Inherited Methods](https://developer.android.com/reference/java/util/stream/DoubleStream#inhmethods)

# DoubleStream


`
public


interface
DoubleStream
`


`


implements

https://developer.android.com/reference/java/util/stream/BaseStream<https://developer.android.com/reference/java/lang/Double, https://developer.android.com/reference/java/util/stream/DoubleStream>


`

|---|
| java.util.stream.DoubleStream |

<br />

*** ** * ** ***

A sequence of primitive double-valued elements supporting sequential and parallel
aggregate operations. This is the `double` primitive specialization of
`https://developer.android.com/reference/java/util/stream/Stream`.

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/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 `https://developer.android.com/reference/java/util/stream/Stream` and the package documentation for [java.util.stream](https://developer.android.com/reference/java/util/stream/package-summary) for additional specification of streams, stream operations, stream pipelines, and parallelism.

<br />

**See also:**

- `https://developer.android.com/reference/java/util/stream/Stream`
- [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/DoubleStream.Builder` A mutable builder for a `DoubleStream`. |
| ` interface` | `https://developer.android.com/reference/java/util/stream/DoubleStream.DoubleMapMultiConsumer` Represents an operation that accepts a `double`-valued argument and a DoubleConsumer, and returns no result. |

| ### Public methods ||
|---|---|
| ` abstract boolean` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#allMatch(java.util.function.DoublePredicate)(https://developer.android.com/reference/java/util/function/DoublePredicate predicate) ` Returns whether all elements of this stream match the provided predicate. |
| ` abstract boolean` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#anyMatch(java.util.function.DoublePredicate)(https://developer.android.com/reference/java/util/function/DoublePredicate predicate) ` Returns whether any elements of this stream match the provided predicate. |
| ` abstract https://developer.android.com/reference/java/util/OptionalDouble` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#average()() ` Returns an `OptionalDouble` describing the arithmetic mean of elements of this stream, or an empty optional if this stream is empty. |
| ` abstract https://developer.android.com/reference/java/util/stream/Stream<https://developer.android.com/reference/java/lang/Double>` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#boxed()() ` Returns a `Stream` consisting of the elements of this stream, boxed to `Double`. |
| ` static https://developer.android.com/reference/java/util/stream/DoubleStream.Builder` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#builder()() ` Returns a builder for a `DoubleStream`. |
| ` abstract <R> R` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#collect(java.util.function.Supplier<R>,%20java.util.function.ObjDoubleConsumer<R>,%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/ObjDoubleConsumer<R> 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. |
| ` static https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#concat(java.util.stream.DoubleStream,%20java.util.stream.DoubleStream)(https://developer.android.com/reference/java/util/stream/DoubleStream a, https://developer.android.com/reference/java/util/stream/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. |
| ` abstract long` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#count()() ` Returns the count of elements in this stream. |
| ` abstract https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#distinct()() ` Returns a stream consisting of the distinct elements of this stream. |
| ` default https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#dropWhile(java.util.function.DoublePredicate)(https://developer.android.com/reference/java/util/function/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 https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#empty()() ` Returns an empty sequential `DoubleStream`. |
| ` abstract https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#filter(java.util.function.DoublePredicate)(https://developer.android.com/reference/java/util/function/DoublePredicate predicate) ` Returns a stream consisting of the elements of this stream that match the given predicate. |
| ` abstract https://developer.android.com/reference/java/util/OptionalDouble` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#findAny()() ` Returns an `https://developer.android.com/reference/java/util/OptionalDouble` describing some element of the stream, or an empty `OptionalDouble` if the stream is empty. |
| ` abstract https://developer.android.com/reference/java/util/OptionalDouble` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#findFirst()() ` Returns an `https://developer.android.com/reference/java/util/OptionalDouble` describing the first element of this stream, or an empty `OptionalDouble` if the stream is empty. |
| ` abstract https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#flatMap(java.util.function.DoubleFunction<?%20extends%20java.util.stream.DoubleStream>)(https://developer.android.com/reference/java/util/function/DoubleFunction<? extends https://developer.android.com/reference/java/util/stream/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. |
| ` abstract void` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#forEach(java.util.function.DoubleConsumer)(https://developer.android.com/reference/java/util/function/DoubleConsumer action) ` Performs an action for each element of this stream. |
| ` abstract void` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#forEachOrdered(java.util.function.DoubleConsumer)(https://developer.android.com/reference/java/util/function/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 https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#generate(java.util.function.DoubleSupplier)(https://developer.android.com/reference/java/util/function/DoubleSupplier s) ` Returns an infinite sequential unordered stream where each element is generated by the provided `DoubleSupplier`. |
| ` static https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#iterate(double,%20java.util.function.DoublePredicate,%20java.util.function.DoubleUnaryOperator)(double seed, https://developer.android.com/reference/java/util/function/DoublePredicate hasNext, https://developer.android.com/reference/java/util/function/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 https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#iterate(double,%20java.util.function.DoubleUnaryOperator)(double seed, https://developer.android.com/reference/java/util/function/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. |
| ` abstract https://developer.android.com/reference/java/util/PrimitiveIterator.OfDouble` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#iterator()() ` Returns an iterator for the elements of this stream. |
| ` abstract https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#limit(long)(long maxSize) ` Returns a stream consisting of the elements of this stream, truncated to be no longer than `maxSize` in length. |
| ` abstract https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#map(java.util.function.DoubleUnaryOperator)(https://developer.android.com/reference/java/util/function/DoubleUnaryOperator mapper) ` Returns a stream consisting of the results of applying the given function to the elements of this stream. |
| ` default https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#mapMulti(java.util.stream.DoubleStream.DoubleMapMultiConsumer)(https://developer.android.com/reference/java/util/stream/DoubleStream.DoubleMapMultiConsumer mapper) ` Returns a stream 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/IntStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#mapToInt(java.util.function.DoubleToIntFunction)(https://developer.android.com/reference/java/util/function/DoubleToIntFunction 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/DoubleStream#mapToLong(java.util.function.DoubleToLongFunction)(https://developer.android.com/reference/java/util/function/DoubleToLongFunction mapper) ` Returns a `LongStream` consisting of the results of applying the given function to the elements of this stream. |
| ` abstract <U> https://developer.android.com/reference/java/util/stream/Stream<U>` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#mapToObj(java.util.function.DoubleFunction<?%20extends%20U>)(https://developer.android.com/reference/java/util/function/DoubleFunction<? extends U> mapper) ` Returns an object-valued `Stream` consisting of the results of applying the given function to the elements of this stream. |
| ` abstract https://developer.android.com/reference/java/util/OptionalDouble` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#max()() ` Returns an `OptionalDouble` describing the maximum element of this stream, or an empty OptionalDouble if this stream is empty. |
| ` abstract https://developer.android.com/reference/java/util/OptionalDouble` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#min()() ` Returns an `OptionalDouble` describing the minimum element of this stream, or an empty OptionalDouble if this stream is empty. |
| ` abstract boolean` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#noneMatch(java.util.function.DoublePredicate)(https://developer.android.com/reference/java/util/function/DoublePredicate predicate) ` Returns whether no elements of this stream match the provided predicate. |
| ` static https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#of(double[])(double... values) ` Returns a sequential ordered stream whose elements are the specified values. |
| ` static https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#of(double)(double t) ` Returns a sequential `DoubleStream` containing a single element. |
| ` abstract https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#parallel()() ` Returns an equivalent stream that is parallel. |
| ` abstract https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#peek(java.util.function.DoubleConsumer)(https://developer.android.com/reference/java/util/function/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. |
| ` abstract https://developer.android.com/reference/java/util/OptionalDouble` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#reduce(java.util.function.DoubleBinaryOperator)(https://developer.android.com/reference/java/util/function/DoubleBinaryOperator op) ` 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 `OptionalDouble` describing the reduced value, if any. |
| ` abstract double` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#reduce(double,%20java.util.function.DoubleBinaryOperator)(double identity, https://developer.android.com/reference/java/util/function/DoubleBinaryOperator op) ` 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 https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#sequential()() ` Returns an equivalent stream that is sequential. |
| ` abstract https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#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/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#sorted()() ` Returns a stream consisting of the elements of this stream in sorted order. |
| ` abstract https://developer.android.com/reference/java/util/Spliterator.OfDouble` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#spliterator()() ` Returns a spliterator for the elements of this stream. |
| ` abstract double` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#sum()() ` Returns the sum of elements in this stream. |
| ` abstract https://developer.android.com/reference/java/util/DoubleSummaryStatistics` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#summaryStatistics()() ` Returns a `DoubleSummaryStatistics` describing various summary data about the elements of this stream. |
| ` default https://developer.android.com/reference/java/util/stream/DoubleStream` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#takeWhile(java.util.function.DoublePredicate)(https://developer.android.com/reference/java/util/function/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. |
| ` abstract double[]` | ` https://developer.android.com/reference/java/util/stream/DoubleStream#toArray()() ` Returns an array containing the elements of this stream. |

| ### 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<https://developer.android.com/reference/java/lang/Double>` | ` 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<https://developer.android.com/reference/java/lang/Double>` | ` 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 (DoublePredicate 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` | `DoublePredicate`: 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 (DoublePredicate 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` | `DoublePredicate`: 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 /> |

### average

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

```
public abstract OptionalDouble average ()
```

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

The computed average can vary numerically and have the
special case behavior as computing the sum; see `https://developer.android.com/reference/java/util/stream/DoubleStream#sum()`
for details.

The average 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 />

##### API Note:

- Elements sorted by increasing absolute magnitude tend to yield more accurate results.

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/OptionalDouble` | an `OptionalDouble` containing the average element of this stream, or an empty optional if the stream is empty <br /> |

### boxed

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

```
public abstract Stream<Double> boxed ()
```

Returns a `Stream` consisting of the elements of this stream,
boxed to `Double`.

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

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/Stream<https://developer.android.com/reference/java/lang/Double>` | a `Stream` consistent of the elements of this stream, each boxed to a `Double` <br /> |

### builder

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

```
public static DoubleStream.Builder builder ()
```

Returns a builder for a `DoubleStream`.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/DoubleStream.Builder` | 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, 
                ObjDoubleConsumer<R> 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 (double element : this stream)
             accumulator.accept(result, element);
         return result;
     
Like `https://developer.android.com/reference/java/util/stream/DoubleStream#reduce(double,%20java.util.function.DoubleBinaryOperator)`, `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 />

| 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` | `ObjDoubleConsumer`: 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 /> |

**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>)`

### concat

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

```
public 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. 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:

      DoubleStream concat = Stream.of(s1, s2, s3, s4).flatMapToDouble(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`.

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

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/DoubleStream` | 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:

      DoubleStream s = DoubleStream.of(1, 2, 3, 4);
           long count = s.peek(System.out::println).count();
       
  The number of elements covered by the stream source is known and the intermediate operation, `peek`, does not inject into or remove elements from the stream (as may be the case for `flatMap` or `filter` operations). Thus the count is 4 and there is no need to execute the pipeline and, as a side-effect, print out the elements.

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

### distinct

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

```
public abstract DoubleStream distinct ()
```

Returns a stream consisting of the distinct elements of this stream. The
elements are compared for equality according to
`https://developer.android.com/reference/java/lang/Double#compare(double,%20double)`.

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/DoubleStream` | the result stream <br /> |

### dropWhile

Added in [API level 35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public 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](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/DoubleStream#generate(java.util.function.DoubleSupplier)`) 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/DoubleStream#sequential()` may improve performance.

##### Implementation Requirements:

- The default implementation obtains the `https://developer.android.com/reference/java/util/stream/DoubleStream#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` | `DoublePredicate`: 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/DoubleStream` | the new stream <br /> |

### empty

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

```
public static DoubleStream empty ()
```

Returns an empty sequential `DoubleStream`.

<br />

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

### filter

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

```
public abstract DoubleStream filter (DoublePredicate 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` | `DoublePredicate`: 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/DoubleStream` | the new stream <br /> |

### findAny

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

```
public abstract OptionalDouble findAny ()
```

Returns an `https://developer.android.com/reference/java/util/OptionalDouble` describing some element of the stream,
or an empty `OptionalDouble` 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/DoubleStream#findFirst()` instead.)

<br />

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

**See also:**

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

### findFirst

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

```
public abstract OptionalDouble findFirst ()
```

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

### flatMap

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

```
public abstract 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
`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` | `DoubleFunction`: 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 `DoubleStream` 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>>)`

### forEach

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

```
public abstract void forEach (DoubleConsumer 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).

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` | `DoubleConsumer`: 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 (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.

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

<br />

| Parameters ||
|---|---|
| `action` | `DoubleConsumer`: 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/DoubleStream#forEach(java.util.function.DoubleConsumer)`

### generate

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

```
public static DoubleStream generate (DoubleSupplier s)
```

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

<br />

| Parameters ||
|---|---|
| `s` | `DoubleSupplier`: the `DoubleSupplier` for generated elements <br /> |

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

### iterate

Added in [API level 35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public 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. The
stream terminates as soon as the `hasNext` predicate returns false.

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

    for (double index=seed; hasNext.test(index); index = next.applyAsDouble(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` | `double`: the initial element <br /> |
| `hasNext` | `DoublePredicate`: a predicate to apply to elements to determine when the stream must terminate. <br /> |
| `next` | `DoubleUnaryOperator`: a function to be applied to the previous element to produce a new element <br /> |

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

### iterate

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

```
public 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.

The first element (position `0`) in the `DoubleStream`
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` | `double`: the initial element <br /> |
| `f` | `DoubleUnaryOperator`: a function to be applied to the previous element to produce a new element <br /> |

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

### iterator

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

```
public abstract PrimitiveIterator.OfDouble iterator ()
```

Returns an iterator for 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/util/PrimitiveIterator.OfDouble` | the element iterator for this stream <br /> |

### limit

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

```
public abstract 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](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/DoubleStream#generate(java.util.function.DoubleSupplier)`) 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/DoubleStream#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/DoubleStream` | 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 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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `mapper` | `DoubleUnaryOperator`: 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 /> |

### mapMulti

Added in [API level 35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public DoubleStream mapMulti (DoubleStream.DoubleMapMultiConsumer 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/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/DoubleStream#flatMap(java.util.function.DoubleFunction<?%20extends%20java.util.stream.DoubleStream>)` on this stream, passing a function that behaves as follows. First, it calls the mapper function with a `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 `flatMap`.

| Parameters ||
|---|---|
| `mapper` | `DoubleStream.DoubleMapMultiConsumer`: 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>>)`

### mapToInt

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

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

<br />

| Parameters ||
|---|---|
| `mapper` | `DoubleToIntFunction`: 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 (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](https://developer.android.com/reference/java/util/stream/package-summary#StreamOps).

<br />

| Parameters ||
|---|---|
| `mapper` | `DoubleToLongFunction`: 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 /> |

### mapToObj

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

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

<br />

| Parameters ||
|---|---|
| `mapper` | `DoubleFunction`: 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<U>` | the new stream <br /> |

### max

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

```
public abstract OptionalDouble max ()
```

Returns an `OptionalDouble` describing the maximum element of this
stream, or an empty OptionalDouble if this stream is empty. The maximum
element will be `Double.NaN` if any stream element was NaN. Unlike
the numerical comparison operators, this method considers negative zero
to be strictly smaller than positive zero. This is a
special case of a
[reduction](https://developer.android.com/reference/java/util/stream/package-summary#Reduction) and is
equivalent to:

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

<br />

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

### min

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

```
public abstract OptionalDouble min ()
```

Returns an `OptionalDouble` describing the minimum element of this
stream, or an empty OptionalDouble if this stream is empty. The minimum
element will be `Double.NaN` if any stream element was NaN. Unlike
the numerical comparison operators, this method considers negative zero
to be strictly smaller than positive zero. This is a special case of a
[reduction](https://developer.android.com/reference/java/util/stream/package-summary#Reduction) and is
equivalent to:

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

<br />

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

### noneMatch

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

```
public abstract boolean noneMatch (DoublePredicate 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` | `DoublePredicate`: 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 DoubleStream of (double... values)
```

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

<br />

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

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

### of

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

```
public static DoubleStream of (double t)
```

Returns a sequential `DoubleStream` containing a single element.

<br />

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

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

### parallel

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

```
public abstract DoubleStream parallel ()
```

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

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

<br />

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

### peek

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

```
public abstract 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](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:

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

| Parameters ||
|---|---|
| `action` | `DoubleConsumer`: 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/DoubleStream` | the new stream <br /> |

### reduce

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

```
public abstract OptionalDouble reduce (DoubleBinaryOperator op)
```

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 `OptionalDouble` describing the reduced
value, if any. This is equivalent to:

    boolean foundAny = false;
         double result = null;
         for (double element : this stream) {
             if (!foundAny) {
                 foundAny = true;
                 result = element;
             }
             else
                 result = accumulator.applyAsDouble(result, element);
         }
         return foundAny ? OptionalDouble.of(result) : OptionalDouble.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 ||
|---|---|
| `op` | `DoubleBinaryOperator`: 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/OptionalDouble` | the result of the reduction <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/DoubleStream#reduce(double,%20java.util.function.DoubleBinaryOperator)`

### reduce

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

```
public abstract double reduce (double identity, 
                DoubleBinaryOperator op)
```

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:

    double result = identity;
         for (double element : this stream)
             result = accumulator.applyAsDouble(result, element)
         return result;
     
but is not constrained to execute sequentially.

The `identity` value must be an identity for the accumulator
function. This means that for all `x`,
`accumulator.apply(identity, x)` is equal to `x`.
The `accumulator` function must be an
[associative](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, and average are all special cases of reduction. Summing a stream of numbers can be expressed as:

      double sum = numbers.reduce(0, (a, b) -> a+b);
       
  or more compactly:

      double sum = numbers.reduce(0, Double::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` | `double`: the identity value for the accumulating function <br /> |
| `op` | `DoubleBinaryOperator`: 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 ||
|---|---|
| `double` | the result of the reduction <br /> |

**See also:**

- `https://developer.android.com/reference/java/util/stream/DoubleStream#sum()`
- `https://developer.android.com/reference/java/util/stream/DoubleStream#min()`
- `https://developer.android.com/reference/java/util/stream/DoubleStream#max()`
- `https://developer.android.com/reference/java/util/stream/DoubleStream#average()`

### sequential

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

```
public abstract DoubleStream sequential ()
```

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

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

<br />

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

### skip

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

```
public abstract 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](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/DoubleStream#generate(java.util.function.DoubleSupplier)`) 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/DoubleStream#sequential()` may improve performance.

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

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/stream/DoubleStream` | 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 DoubleStream sorted ()
```

Returns a stream consisting of the elements of this stream in sorted
order. The elements are compared for equality according to
`https://developer.android.com/reference/java/lang/Double#compare(double,%20double)`.

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/DoubleStream` | the result stream <br /> |

### spliterator

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

```
public abstract Spliterator.OfDouble spliterator ()
```

Returns a spliterator for 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/util/Spliterator.OfDouble` | the element spliterator for this stream <br /> |

### sum

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

```
public abstract double sum ()
```

Returns the sum of elements in this stream.

Summation is a special case of a [reduction](https://developer.android.com/reference/java/util/stream/package-summary#Reduction). If
floating-point summation were exact, this method would be
equivalent to:

    return reduce(0, Double::sum);
     
However, since floating-point summation is not exact, the above code is not necessarily equivalent to the summation computation done by this method.

The value of a floating-point sum is a function both
of the input values as well as the order of addition
operations. The order of addition operations of this method is
intentionally not defined to allow for implementation
flexibility to improve the speed and accuracy of the computed
result.

In particular, this method may be implemented using compensated
summation or other technique to reduce the error bound in the
numerical sum compared to a simple summation of `double`
values.

Because of the unspecified order of operations and the
possibility of using differing summation schemes, the output of
this method may vary on the same input elements.

Various conditions can result in a non-finite sum being
computed. This can occur even if the all the elements
being summed are finite. If any element is non-finite,
the sum will be non-finite:

- If any element is a NaN, then the final sum will be NaN.
- If the elements contain one or more infinities, the sum will be infinite or NaN.
  - If the elements contain infinities of opposite sign, the sum will be NaN.
  - If the elements contain infinities of one sign and an intermediate sum overflows to an infinity of the opposite sign, the sum may be NaN.

It is possible for intermediate sums of finite values to overflow into opposite-signed infinities; if that occurs, the final sum will be NaN even if the elements are all finite. If all the elements are zero, the sign of zero is *not* guaranteed to be preserved in the final sum.

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

<br />

##### API Note:

- Elements sorted by increasing absolute magnitude tend to yield more accurate results.

| Returns ||
|---|---|
| `double` | the sum of elements in this stream <br /> |

### summaryStatistics

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

```
public abstract DoubleSummaryStatistics summaryStatistics ()
```

Returns a `DoubleSummaryStatistics` describing various summary data
about the elements of this stream. 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 />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/DoubleSummaryStatistics` | a `DoubleSummaryStatistics` describing various summary data about the elements of this stream <br /> |

### takeWhile

Added in [API level 35](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public 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](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/DoubleStream#generate(java.util.function.DoubleSupplier)`) 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/DoubleStream#sequential()` may improve performance.

##### Implementation Requirements:

- The default implementation obtains the `https://developer.android.com/reference/java/util/stream/DoubleStream#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` | `DoublePredicate`: 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/DoubleStream` | the new stream <br /> |

### toArray

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

```
public abstract double[] 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 ||
|---|---|
| `double[]` | an array containing the elements of this stream <br /> |