Optional used as method argument? (original) (raw)

Vitaly Davidovich vitalyd at gmail.com
Fri Oct 2 13:00:03 UTC 2015

Optional really needs value types to be used more widely in these contexts. Given a language that doesn't have non-null baked into the type system or language, the next best thing would be a library solution. It's much better to indicate nullability in the parameter type rather than javadoc; the javadoc should still explain what a null value would imply for the method, but it's a poor substitute for encoding that fact.

Also, having consumeAValue vs consumeNoValue type of approach doesn't scale all that well with more than a single nullable parameter. Unfortunately, there's no good solution in java at the moment; before someone suggests using annotations, let me say they're helpful, but just a bandaid.

On Fri, Oct 2, 2015 at 8:49 AM, Roger Riggs <Roger.Riggs at oracle.com> wrote:

+1

The "no such value" makes me curious about the context. The @param tag really should be saying something about the parameter. The absence of an @throws (or class/package wide spec) documenting the NPE for nulls would indicate that null is allowed. Roger

On 10/2/2015 4:10 AM, Remi Forax wrote: Hi Max, yes, It's usually not a good idea, creating an Optional is like a boxing, you create an object (and prey that escape analysis will work), usually null means there is no value so either you have two methods consume, something like consumeAValue(String) and consumeNoValue() or you have one method consumeAValue and you don't call it if there is no value. regards, Rémi ----- Mail original -----

De: "Wang Weijun" <weijun.wang at oracle.com> À: core-libs-dev at openjdk.java.net Envoyé: Vendredi 2 Octobre 2015 03:25:43 Objet: Optional used as method argument?

I hear people saying Optional is usually used as return values. Can I use it as an argument, like this? void consume(Optional value) This way, I don't need to add spec like "@param value can be null if there is no such value". Thanks Max

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