You get that with Java 8 and later because you can just define a FunctionalInterface and then use a mapping table to function-to-use and it gets really compact. If you want to decorate arbitrary functions that should be fairly trivial too.

Wrote something small like that for a random data generator for an in-house properties tester in Java a short while back. It makes it easier, in my opinion, when you have all the code available in a single screen than if it’s spread out.