An ad-hoc polymorphism way to create a stream

[Patrick Reinhart]

Hi Remi,

That was also the first failed lookup try after starting with Lambdas, specially because we got a lot of own implementation implementing Iterable. It would have been more natural from me to find some according methods on the Stream interface. Especially as a beginner.

Cheers Patrick

Am 16.11.2013 um 15:00 schrieb Remi Forax <forax at univ-mlv.fr>:

> During Devoxx Belgium, after the talk of Brian and Jose Paumard, there was an interesting discussion among some Java8 early adopters about the fact that in the API there no xommon way to get a Stream for anything that is conceptually a collection.
> 
> I propose to introduce the following new methods on Stream:
> 
>  /**
>   * Returns a sequential|Stream|  with the iterable as its source.
>   *
>   * @param T the type of stream elements.
>   * @param iterable the iterable used as source of the stream.
>   * @return a sequential stream.
>   */
>  public static <T> Stream<T> from(Iterable<T> iterable) {
>      return StreamSupport.stream(iterable.spliterator(), false);
>  }
> 
>  /**
>   * Returns a sequential|Stream|  with the collection as its source.
>   *
>   * @param T the type of stream elements.
>   * @param collection the collection used as source of the stream.
>   * @return a sequential stream.
>   */
>  public static <T> Stream<T> from(Collection<T> collection) {
>      return collection.stream();
>  }
> 
>  /**
>   * Returns a sequential|Stream|  with the array as its source.
>   *
>   * @param T the type of stream elements.
>   * @param array the array used as source of the stream.
>   * @return a sequential stream.
>   */
>  public static <T> Stream<T> from(T[] array) {
>      return Stream.of(array);
>  }
> 
> These methods are like the of() methods but of() overloads deal with values while from() deal with collections.
> 
> This also re-introduce a way to get a stream from an unknown Iterable that was removed from Iterable
> because we want implementation of Iterable to be able to return Stream of primitives.
> I know that this is late in the game, but I think that given these methods just delegates to existing methods,
> it will be better to introduce them in Java8 than in Java9.
> 
> cheers,
> Rémi
>