Hi, I'm a rookie developer and I only know basic Java (the only language that I'm learning/focusing at the moment, ). My question is, can anyone point me at the right direction or tips what game engines should I use, I only know LibGDX but haven't tinkered with it that much. I'm really itching on developing not just games but useful programs as well that can be used on a daily basis. I always see C# (Unity) and C++ most of the time thinking that my knowledge at this language will just go to waste. Thanks and good day!

Game developers like to compare their engines like men compare dick sizes. Stick with what you know, many great games have been made with LibGDX and or other Java game engines, frameworks.

Java has gained a bad reputation over the years because of the low performance it had in the past, but it is not a bad language, it merely has a couple bad warts.

Not sure if I understood you correctly, did you mean to make “useful programs” with LibGDX? That’s probably not a good idea.

LibGDX looks popular as many games were developed with LibGDX on Itch.io!
https://itch.io/games/made-with-libgdx

Our former programmer used Java and LibGDX for Intra-System: Trust Issues and it worked good for him. 

The only real problems we had were on another game with big graphics (4K graphics), that was easier for him in Engines but I don't know all the details (maybe it has something to do how the VRam is managed).