Thanks again everyone. I am just finishing up the course I was about to take when I started this thread. I decided to program my game's visuals in JavaFX, and while I've heard it's much better than Swing, I often have trouble finding reliable information on it. I probably shouldn't have decided to try and program the whole thing in native Java instead of JavaFX's XML-style notation, "FXML". 

Hello RidiculousName,

In my opinion, Java is much easier to get started with than C++ and its libraries are higher level.

I recommend checking out libGDX.

However, the best engine to go with would be Unity, it uses C# which is quite similar to Java.

As for performance, you don't have to worry much about it in indie games, only one thing to keep in mind: use pooling for frequently created/destroyed resource heavy objects, for example bullet sprites. Most java game libraries provide an easy to use implementation for such object pool.