This file https://github.com/mmhelloworld/idris-jvm/blob/main/libs/bas... demonstrates how the interop looks like currently. The `%foreign` directive takes an FFI descriptor to talk to the respective backends. Here you can see few scheme and JVM descriptors starting with "scheme:" and "jvm:" respectively. The JVM descriptors there show constructor calls `<init>`, instance methods `.lock` and static methods `getThreadData`.

I can't speak for the JVM backend specifically, but in general Idris 2 code can call arbitrary functions in the backend with the "%foreign" pragma. So hopefully that would be supported for Java, although I don't know how it would work with classes.