Behavior of concat(null)

[Brian Goetz]

Its pretty reasonable for (1) to throw NPE.

On 11/19/2012 5:57 PM, Remi Forax wrote:
> Elena,
> just to understand do you try to call
>     1) stream.concat(null);
> or
>     2) stream.concate(stream2);    // with some null in stream2
>
> for case 1) concat should throw a NPE, for case 2) see the answer of
> Brian :)
>
> Rémi
>
> On 11/19/2012 04:57 PM, Brian Goetz wrote:
>> 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
>>>
>
>