How do I install java-oo into my installation of Java?

[BenHut1]

I don't have an IDE, just running javac.exe from the command line. So how do I use java-oo here?

[amelentev]

Please read the readme, javac section.
https://github.com/amelentev/java-oo?tab=readme-ov-file#javac-ant-etc
Just download the jar and run javac.exe -cp javac8-oo-plugin.jar ...