API question/request: Array to Stream

[Arne Siegel]

I think the current API decisions regarding stream creation from arrays are
a bit dangerous. Look at this example, based on a theme from Josh Blochs
Effective Java:

        IntStream is1 = IntStream.of(1,2,3,5);
        System.out.println("Number of elements in stream: " +
is1.count());   // --> 4

        Stream is2 = Stream.of(1,2,3,5);
        System.out.println("Number of elements in stream: " +
is2.count());   // --> 4

        int[] data = {6,7,8,7};

        IntStream is3 = Arrays.stream(data);
        System.out.println("Number of elements in stream: " +
is3.count());   // --> 4

        IntStream is4 = IntStream.of(data);
        System.out.println("Number of elements in stream: " +
is4.count());   // --> 4

        Stream is5 = Stream.of(data);
        System.out.println("Number of elements in stream: " +
is5.count());   // --> 1 !!!!




2013/10/2 Remi Forax <forax at univ-mlv.fr>

> On 10/02/2013 11:02 AM, Paul Sandoz wrote:
> > On Oct 2, 2013, at 10:07 AM, Gernot Neppert <mcnepp02 at googlemail.com>
> wrote:
> >
> >> Oops, I hadn't noticed there were 2 factory methods at different places
> >> doing exactly the same thing.
> >> Won't this perpetually provoke the question "Which one should I use?"
> >>
> > In this case i think it is mostly harmless; the answer being "which ever
> one you prefer" (they are effectively the same thing).
>
> And it's not the first time that we have the same method at two places,
> by example Integer.toString(int) and String.valueOf(int).
> if one call the other, as Paul said, it's more to avoid a discovery
> problem.
>
> >
> >
> >> Since java.util.Arrays has such a complete set of Stream-creation
> methods,
> >> maybe one could drop Stream.of(T...) in favour of Arrays.stream(T...)?
> >>
> > The problem with Arrays, as with other factory creation methods, is it
> can be often hard to find things.
> >
> > So we have placed a few static factory methods on Stream itself, and
> Stream.of serves the duel purpose of creating a stream from an explicit
> enumeration of elements or from an array of elements.
> >
> > Note that we have avoided adding List.of etc (as proposed by Stephen)
> due to time constraints but also because it is likely we can do better with
> collection literals.
>
> and Collection literals was one item of project coin that was delayed
> and moved from jdk7 to jdk8 :)
>
> >
> > Paul.
>
> Rémi
>
>
>