jMonkeyEngine is a game development suite made especially for game developers who want to create 3D games with modern technology standards. The software is programmed entirely in Java, intended for wide accessibility and quick deployment.
Likely the best Java game engine. Here is why:
PROS:
+ Very well documented
+ Mature code base
+ Great support for Blender files (models, animations, materials, etc.)
+ Commercial friendly open-source BSD license
+ Active community
+ Convenient multi-platform support without needing to cross-compile any code
+ Supports Android (even with native Bullet support!)
CONS:
- Physics has minor glitches, though that's more related to Bullet
- The SDK is only available for Netbeans. However, the engine itself is completely IDE independent.