IMHO the problem with Java 8 is not the language but framework support. Except SparkJava, most other frameworks use Java 8 as a "upgraded java compiler". Tge canonical way to write code is still Java 6.

I think the best way to upgrade your java codebase is Kotlin. On the server side, Kotlin +vertx is extremely compelling.. on the Android side, Kotlin pretty much kills it.

I agree. This is exactly the move I've made when I was CTO of a company needing a move to the JVM from .NET. Given the options of Java, Scala - I moved to picking Kotlin. In many ways, Kotlin for me is Scala without the different ways to hang yourself. I wish it was given more credit that it gets right now outside of the Android circles.

that is very interesting!

could you talk about the framework that you used? im particularly concerned about ORM and database connectivity.

If by framework you mean web framework, I've used Dropwizard. It's a lean and mean modern-java option, and it's not a Kotlin native thing (you do have these). You can use any Kotlin or traditional Java framework out there transparently (that's a good value of Kotlin).

For ORM, Dropwizard and its ecosystem got you covered.

Also dropping out to Java when ever you want can be done in the same project (which I encouraged) seamlessly both in terms of how Java and Kotlin interoperate, and in terms of Intellij, which is first-class in both languages because Kotlin is Jetbrains' baby, and, because Java has been best supported by Intellij for ages (can't really find that kind of thing anywhere else).