So I just installed Ubuntu, and this is my first time working in a Linux environment, so bear with my noobishness here.
Anyway, I downloaded the Java 8 JDK directly
After adding the JDK repo, before Installing you might want to run an update first so the repo can be added run apt update
JDK
apt update
an then continue with your installation sudo apt install adoptopenjdk-8-hotspot
sudo apt install adoptopenjdk-8-hotspot