Javadoc in 9 seems to treat all interfaces with only one method as functional interfaces

[Paul Benedict]

It's about design intent. The annotation conveys the intent and the
compiler enforces it by ensuring one abstract method exists.

As you noted, there are such things as "implicit functional interfaces",
but use them at your own risk. In theory, an interface not annotated with
@FI can gain additional methods in the future, which would then break any
implicit use you relied on.

Paul


On Thu, Mar 20, 2014 at 3:30 PM, Florian Weimer <fw at deneb.enyo.de> wrote:

> * Paul Benedict:
>
> > It's a bug because it was an early decision in JDK 8 that got changed:
> >
> http://mail.openjdk.java.net/pipermail/lambda-libs-spec-experts/2013-November/002379.html
> >
> > And then the change:
> >
> http://mail.openjdk.java.net/pipermail/core-libs-dev/2014-January/024165.html
>
> So it's a functional interface, but the documentation doesn't say so
> because we don't want it to be a functional interface?  That's rather
> odd and suggests that something went wrong with the design. :-)
>



-- 
Cheers,
Paul