Behavior of allMatch, anyMatch and noneMatch for empty Stream

[Peter Levart]

But isn't checking for null going to defeat any possible future
optimizations that could optimize the object away?

Peter
On Dec 12, 2012 5:51 PM, "Remi Forax" <forax at univ-mlv.fr> wrote:

> On 12/12/2012 03:22 PM, Vitaly Davidovich wrote:
> > Brian,
> >
> > I think NPE should be thrown when predicate is null irrespective of
> stream
> > length for consistency sake.
> >
> > Thanks
>
> yes, it this should be true for any parameters that are typed by a
> functional interface at least in java.util and java.util.stream.
> We don't want user to send null as a lambda exactly like we don't want
> user to send a null enum.
>
> Rémi
>
> >
> > 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
> >>>
> >>
>
>
>