Design for collections upgrades
brian.goetz at oracle.com
Tue Mar 8 12:27:36 PST 2011
> List<String> things = ...
> Collection<String> fooAbles = things.filter(#Thing.isFoo); // ooh, pretty
> Not that pretty because filter have to create a new collection and
> there is no way to do that apart hard coding a new ArrayList somewhere.
> It's better in my opinion to have a filterTo that takes a collection
> as argument.
> Collection<String> fooAbles = things.filterTo(#Thing.isFoo, new HashSet<>());
This works just fine when there's one operation in the pipeline, but
starts to get clunky when the pipeline has multiple steps and you are
explicitly specifying the "new ArrayList<>()" a bunch of times.
On the other hand, this works much better in the serial/lazy case, since
the only place you need to choose a collection type is (typically) at
the end of the pipeline:
fooableWeights = foos.toStream()
and we should definitely do this for the stream case.
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