Recently I decided I wanted to start coding JAVA, specifically for games.
I decided to start off simple and make a 2d game, but I cannot even get the display to work!

I used the YouTuber DesignsByZephyr's series to start me off and so I can learn basic techniques when it comes to coding games, but I cannot make the screen work. I analyzed his works and compared it to mine, but I can't find any differences.

I was hoping that one of you guys could help me fix this problem.

I have links to the code I put in here:

Here is the link of DesignsByZephyr's tutorial that I am stuck on:
Displaying the Sprite Sheet - YouTube

And for those brave enough, here is the .zip file of EVERYTHING so you can save time. If you want to stay safe and use the other links, I'm cool with that too:
Test Game

Here is the order of the files I have put them in:
-Test Game
-- ---Sprite_Sheet.png