If we've got Visual Studio up, might as well throw in a vote for eclipse - https://eclipse.org/downloads/
As I do most of my work by hand, and my day job features it, it's what I use. Platform has drastically improved since they pushed the Luna re-release, now comes with an inbuilt dark theme that doesn't suck (mandatory for constant programming I find, especially at night) and Java as a whole is really pushing usability improvements since 8 was released.
(automatic generic classpath var, no more multiple conflicting Java versions, eclipse has an auto-installer / updater, all sorts of nice stuff. As someone who's used eclipse since Ganymede and Java since 1.5, these are actual real improvements I value)
Note: is an IDE for programming, is not a game engine. Use at your peril, Your Mileage Will Vary :P