Hey, after searching quite a bit, I haven’t really found a great solution for 2d game programming in Java. I have been using SDL in C++ and have been very happy with it, but I would like to give Java a try. I see the Java Monkey Engine is popular, but is it advisable to use it for a strictly 2d game? I am interested in using a pre-made game engine, as I don’t really have the time to build one from scratch. I was tempted to use Pygame and the other Python tools, but I would prefer to use Java. Thanks for any help.
yup must agree ATM best 2d engine is Slick.
Slick provides a lot of tools, but nothing that I’d actually call an engine. There are a lot of alternatives in Java:
GTGE
GAGE
EasyWay
SPGL
JASEL
Stencyl
JGame
PulpCore
Kev
Well actually there is a java port of SDL 
So if you´re happy with SDL, you can use SDL with java
Source Code: http://btrgame.com/dev/srconline.jsp
Demo: http://btrgame.com/game/game.jsp
Download: http://btrgame.com/dev/
Most every one of the frameworks mentioned previously are for 2d graphics rendering or action games (creation, loop, render) where the unit of importance is framerate and most objects are non-persistent.
If you are interested in a multiplayer game, a single-player turn-based game (or hybrid), or really any kind of puzzle game, I haven’t seen any game application frameworks I’d recommend. Maybe I’m just looking in the wrong places.