RFR 8071597 Add Stream dropWhile and takeWhile operations

[Paul Sandoz]

On Jun 4, 2015, at 10:27 AM, Peter Levart <peter.levart at gmail.com> wrote:
> 
> On 06/03/2015 08:53 PM, Peter Levart wrote:
>> Hi Paul,
>> 
>> This is a usefull addition to Stream API for sequential ordered streams. But does it have any utility in unordered streams at all? Wouldn't it be better to just throw an IllegalStateException or something if the stream is not ordered? I can't imagine currently a situation where I would need to select an arbitrary sub-set of the stream where all elements match a predicate and I would not be given any guarantee about how big a subset I will get - the same with a stream where an arbitrary sub-set of elements matching predicate is taken away. If I wanted something similar for unordered stream, I would rather say: "Give me at most N elements of the stream matching predicate" for example - and that can already be achieved by .filter().limit();
>> 
>> So any use of [take|drop]While on unordered stream would most probably be unintended and consequently could be considered a bug, don't you think?
> 
> Ok, I take back. I was only thinking in terms of the [take|drop]While Predicate being a function of the stream element. Now that I see an example where it is a function of time, I can understand it's utility even for unordered streams.
> 

Right, i was about to reply pointing out that aspect.

This is a tricky area, i expect it will keep some people rather busy on stackoverflow :-)

Paul.