first off you question sounds like "how do I do first class functions in java" historically that answer was "make a class with one method, it's shit suck it" things are better now though.

Prior versions of Java also lack predefined functional interfaces and first-class functions such as filter and map. Java 8 reduces verbosity largely by introducing lambdas and method references to ...

Serverless computing becomes a focus at JavaOne 2017, as Oracle introduces Project Fn and Microsoft previews Java support for Azure Functions.