SDKMAN is the SDK Manager, a tool used at large by the alternate JVM language crowd for installing SDKs like Groovy, Scala, Ceylon, Grails, Gradle, SBT and many more. It's similar to rvm, but is focused on all JVM languages.

It would be great to have JRuby on there too. This would involve the JRuby team pushing their own releases to SDKMAN via the Vendor API. It usually involves 3 REST calls hooked into your release build pipeline. Details of the API and process can be found on the SDKMAN Vendors page.