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stickfigure 7 months ago

The parent certainly knows this. Additional methods could be added to `Map` which return `Optional`. I am annoyed by their absence every day.

pbh101 7 months ago | parent [-]

Maybe. They didn't seem to communicate any specific knowledge of the Java standard library. Agree an

    Optional<V> get(K) 
sounds like an 'obvious' addition, though also I've found that when something 'obvious' isn't added to Java since 1.7, the explanation proffered makes sense to me.
cogman10 7 months ago | parent [-]

Java doesn't have return type function dispatch.

If you had something like:

    var x = map.get(k);
The type of `x` could not be inferred.

The best they could hope for is a signature like `Optional<V> getOpt(K);`. Which wouldn't be terribly bad as Java currently has an annoying get definition in the `Map` interface because it predates generics (The current signature is `V get(Object)`).

Regardless, if they do want to change the interface, it'd probably be best if they waited for Valhalla to land. One of the problems with `Optional` as it stands is it creates a load of GC pressure. If `Optional` is converted into a value class then there will be effectively no overhead to returning it everywhere.