Sorting streams containing nulls

[Georgiy Rakov]

Hello,

could you please provide more explicit answer.

Details:
You've said that nulls are allowed so imagine we have a stream 
containing some nulls. Than we want to sort it.

Here I see following contradiction.
 From the one hand if nulls are allowed they should be treated properly. 
It means when the sequence is sorted nulls should honestly be passed to 
supplied comparator and moved to its place in accordance with the result 
returned by comparator. This could not be done if NPE is thrown by 
implementation.
 From another hand you've said that nulls should be filtered out 
otherwise NPE is thrown.

So could you please answer explicitly:
- if this situation is considered as a bug and is going to be fixed; by 
"this situation" I mean the fact that NPE is thrown while sorting the 
stream containing nulls as described in my original message below;
- or whether this situation is considered as expected behavior.

Thanks,
Georgiy.

On 13.11.2012 21:15, Howard Lovatt wrote:
> The expert groups has decided to go with allowing nulls and using an Option type and as a result if you don't filter out nulls [.filter(x->x!=null)] then you will get NPE. My preference would be for nulls to be banned, like ConcurrentHashMap does. But it is hardly the end of the world, just annoying that you have to put filters in if in doubt.
>
> Sent from my iPad
>
> On 13/11/2012, at 4:08 PM, Georgiy Rakov<georgiy.rakov at oracle.com>  wrote:
>
>> On 07.11.2012 18:08, Sergey Kuksenko wrote:
>>> But it is sorted stream.
>>> How should we compare null with other values?
>> The supplied comparator could treat nulls in a special way. There are
>> some ways to do it for instance:
>> - comparator could consider null as the lowest value;
>> - when sorting integers comparator could consider null being equal to
>> some integer value for instance 5;
>>
>> Georgiy
>>
>>> On 11/07/2012 05:43 PM, Remi Forax wrote:
>>>> On 11/07/2012 02:30 PM, Brian Goetz wrote:
>>>>> The exact specification is not yet written, but we are not expecting stream implementations or operations to do anything special with nulls.  This means nulls may be passed to lambdas or inserted into collections that do not support them, resulting in NPE.
>>>> so it's an implementation bug ?
>>>> All Queue don't accept null so either null need to be masked/unmasked or
>>>> the implementation has to be changed.
>>>>
>>>> Rémi
>>>>
>>>>>
>>>>> On Nov 7, 2012, at 5:22 AM, Georgiy Rakov wrote:
>>>>>
>>>>>> Hello.
>>>>>>
>>>>>> When we make sorted(...).iterator() on Stream instance containing one
>>>>>> ore more nulls we receive NPE. The example of stack trace is below:
>>>>>>
>>>>>>       java.lang.NullPointerException
>>>>>>            at java.util.PriorityQueue.offer(PriorityQueue.java:320)
>>>>>>            at java.util.PriorityQueue.add(PriorityQueue.java:306)
>>>>>>            at java.util.streams.ops.SortedOp.iterator(SortedOp.java:105)
>>>>>>            at java.util.streams.ops.SortedOp.wrapIterator(SortedOp.java:97)
>>>>>>            at
>>>>>>       java.util.streams.AbstractPipeline.iterator(AbstractPipeline.java:329)
>>>>>>            ...
>>>>>>
>>>>>> Could you please tell if it is considered as expected behavior or it's
>>>>>> going to be fixed somehow.
>>>>>>
>>>>>> Georgiy.
>>>>>>