This was your problem. Programming Java without an IDE that recompiles your changes on the fly is just so arcane and really slows you down as you noticed.
Which is great, but that's almost not the main issue. In the ipython REPL I can work with my code and data at the same time. It's a huge disadvantage to not be be able to probe your data to create a working process.
The Java VM has hot code swapping builtin (IIRC limited to method bodies but the commercial JRebel drops that limitation).
Start your program in your IDE's debugger (or point it to your application server where your program is running) and you can change the code immediately, rerun your methods, change variables, inspect the objects, etc.
It's more than a simple REPL, it's a full-blown debugger and it comes really close to what you have in a SmallTalk image where your code, data, and environment is all the same.