On a mac and having trouble downgrading java 9-12 to 8 so you can use technic/forge? Well, I have created a script that automatically will remove java so you can install your older version.
Read more here- https://smacpats.github.io/javauninstaller/
Source code- https://github.com/smacpats/Java-Uninstaller-Macos
5 Years on Minecraftforum. Over 9 on minecraft itself. Mod developer for 4 years.