[RandomSort]

I'm going to say Groovy. It allows you to do all the nifty things Java does, but you just feel infinitely more productive.

[vorg]

Apache Groovy brought closures to the JVM in its day, something no other JVM language had at the time, kudos to its creator James Strachan who was dissatisfied with Beanshell. Now that Java 8, Kotlin, Scala, and Clojure also brought closures/lambdas mainstream, I'm not really sure what unique proposition Groovy brings to the JVM any more.

[ktkization]

Grails is an amazing powerful web framework. Favorite feature of it is GORM. Quite expressive