Behavior of allMatch, anyMatch and noneMatch for empty Stream

[Vitaly Davidovich]

Brian,

I think NPE should be thrown when predicate is null irrespective of stream
length for consistency sake.

Thanks

Sent from my phone
On Dec 12, 2012 9:16 AM, "Brian Goetz" <brian.goetz at oracle.com> wrote:

> These values are correct.
>
> All/None match correspond to universal quantification, which can be
> vacuously satisfied; Any match corresponds to existential
> quantification, which cannot.
>
> On 12/12/2012 6:26 AM, elena votchennikova wrote:
> > Hi,
> >
> > please clarify behavior of allMatch(Predicate), anyMatch(Predicate) and
> > noneMatch(Predicate) methods for empty Stream.
> >
> > 1) Please look at the next code:
> > System.out.println(Streams.emptyStream().allMatch(o -> true));
> > System.out.println(Streams.emptyStream().anyMatch(o -> true));
> > System.out.println(Streams.emptyStream().noneMatch(o -> true));
> >
> > The result output will be:
> > true
> > false
> > true
> >
> >
> > Is it OK? And will such behavior be specified?
> >
> > 2) Methods allMatch, anyMatch and noneMatch throw NullPointerException
> > if Predicate is null, for example:
> > Stream notEmptyStream = Arrays.stream(new Object[] {new Object()});
> > notEmptyStream.allMatch(null);
> >
> > But if Stream is empty methods will not throw NPE.
> > So, next code will print same result as in point 1)
> > System.out.println(Streams.emptyStream().allMatch(null));
> > System.out.println(Streams.emptyStream().anyMatch(null));
> > System.out.println(Streams.emptyStream().noneMatch(null));
> >
> > Is it OK or calling these methods with null-Predicate should throws NPE?
> >
> >
> >
> > Best regards,
> > Elena
> >
>
>