Behavior of concat(null)

[Brian Goetz]

We do not guarantee that any given operation WILL or WILL NOT throw NPE 
when present with nulls.  We have made some efforts to avoid throwing 
NPEs from within the Streams library code, but even that is not 
guaranteed (put that in the "reasonable efforts" category.)  We expect 
most, but not all, NPEs resulting from null elements to come from code 
outside java.util.stream, such as lambdas passed to the operation, 
Arrays.sort(), the constructor of Optional, etc.

On 11/19/2012 10:17 AM, elena votchennikova wrote:
> Hello,
>
> I'm trying to use method concat(Stream) of some Stream implementation
> with null-argument and currently it doesn't throw NullPointerException.
> Exception is thrown only when I call some method of the resulting
> Stream, for example iterator().
>
> Could you please explain - is it an expected behavior or concat() with
> null-argument should throw NPE?
>
>
> Thanks a lot,
> Elena
>