Java/Maven and Scala/sbt projects share immutable thing

Question

Project 1: a Java/Maven project

Project 2: a Scala/sbt project

Thing: generally, an immutable object instantiated in from 3rd party Java library. For example, ThingBuilder.foo("bar").build()

Question: How can I define Thing in only one place, and have it used both in Project 1 and 2? (So the parameters in ThingBuilder are guaranteed to be the same in both projects.)

• candied_orange: Just to be clear. In your example there are two different executables from the two projects running in two different JVM's. You're not simply trying to reuse a class defined in one language in the other language. Right?
• Pete: Exactly. Perhaps the best way is to make Project 3, having Project 3 jar as a dependency in both, with some wrapper object to produce Thing. I don't really know! And would I do it in Java or Scala :)
• candied_orange: Er no, what I want to know is if you're trying to share runtime state between two running executables, one of which has created the Thing object with a certain state and the other did not but wants to use it in that state. Or if you just want to be able to define Thing with a java class in the java project but create it as an object in your scala project where you would give it state and not share that object with the java/maven project.
• Pete: The second goal: define it in a single place, instantiate it in both projects, but the instantiated objects are not shared/an instantiated object is not shared. The two executables communicate through a messaging system, so it's important they work with the same definition of Thing, but they don't share an instance of it directly.

Answer 1

One way would be to create a library wrapping the creation of the immutable object, and have it's creation driven by a shared config file.

lightbend's config is useful for this because it's implemented in Java, despite being a lightbend project.