Sized Collector supplier

Tagir Valeev amaembo at
Tue Sep 18 15:19:47 UTC 2018


See the ticket:

In my opinion only toList and toUnmodifiableList collectors would benefit
significantly, but this could be solved in alternative way, adding the
corresponding methods to the stream interface. Another possibility is to
add a hidden API for this case (e. g. add new method to CollectorImpl and
branch on `instanceof CollectorImpl` inside ReferencePipeline.collect`).
This would add a performance benefit for JDK collectors and JDK stream
implementation without exposing new API. If somebody interested, I can
implement this. In general I don't think that improvement of a couple of
collectors performance justifies increasing public API complexity.

To my opinion Collectors would benefit much more if they support
short-circuiting. There are much more interesting use-cases which could be
covered with short-circuiting collectors.

With best regards,
Tagir Valeev.

вт, 18 сент. 2018 г., 16:39 Roman Leventov < at>:

> Is there a reason why doesn't support sized
> supply of a mutable result container? It seems that it could be hugely
> beneficial when the size of the stream is known, e. g. for precise
> ArrayList and HashMap.

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