If you look into the Java Gaming Resources
, we usually recommend:Developing Games in Java by David Brackeen
andKiller Game Programming in Java by Andrew Davison
These books may be old and use Java2D, however their methods still apply and are educational for a newcomer to understand how things in games work - no OpenGL here but you should learn that later.
I specifically recommend the Brackeen book. Killer Game Programming has its flaws and one third of the book is about Java3D which is practically useless, especially today.
I should also stretch that, while some people here may recommend that you learn OpenGL, it is by no means necessary to do so, unless you want to specifically become a graphics programmer.
I have a team, we use Libgdx. We have one guy who is a OpenGL wiz and does stuff - however for a "normal" game, using Libgdx you never have to use OpenGL directly. At most you have to familiarize yourself with some OpenGL facts, how things work, but you dont have to actually code "low level".
So not discouraging or anything, not at all. Just know: Only do it if it really interests you and/or you have benefits in reaching your goals when doing it.