----- Mail original -----
> De: "Nir Lisker" <[email protected]>
> À: "core-libs-dev" <[email protected]>
> Envoyé: Lundi 14 Septembre 2020 20:56:27
> Objet: 'Find' method for Iterable
> Hi,
>
> This has probably been brought up at some point. When we need to find an
> item in a collection based on its properties, we can either do it in a
> loop, testing each item, or in a stream with filter and findFirst/Any.
>
> I would think that a method in Iterable<T> be useful, along the lines of:
>
> public <T> Optional<T> find(Predicate<T> condition) {
> Objects.requireNonNull(condition);
> for (T t : this) {
> if (condition.test(t)) {
> return Optional.of(t);
> }
> }
> return Optional.empty();
> }
>
> With usage:
>
> list.find(person -> person.id == 123456);
>
> There are a few issues with the method here such as t being null in
> null-friendly collections and the lack of bound generic types, but this
> example is just used to explain the intention.
>
> It will be an alternative to
>
> list.stream().filter(person -> person.id == 123456).findAny/First()
> (depending on if the collection is ordered or not)
>
> which doesn't create a stream, similar to Iterable#forEach vs
> Stream#forEach.
>
> Maybe with pattern matching this would become more appetizing.
During the development of Java 8, we first tried to use Iterator/Iterable
instead of using a novel interface Stream.
But a Stream cleanly separate the lazy side effect free API from the mutable
one (Collection) and can be optimized better by the VM (it's a push API instead
of being a pull API).
The other question is why there is no method find() on Collection, i believe
it's because while find() is ok for any DB API, find() is dangerous on a
Collection because the execution time is linear, so people may use it instead
of using a Map.
>
> - Nir
Rémi
