[javajosh]

Haven't used it, but I can't imagine it would be great. Java's issue is that you can't do anything outside of a class. So there really is no outside context in which a REPL makes conceptual sense.

[jerven]

Well it is not that rigid. You can do code outside of a class/method

  jshell> var x=8
  x ==> 8

  jshell> x*3
  $2 ==> 24

etc.

But I haven't used it either as I never worked with a REPL other than SQL clients.