macOS Eclipse- Running non-project files

I recently started using Eclipse, and it seems well-designed. I am, however, having an idiot problem with it.

I already have many java class files written, but they're not incorporated into projects. Is there any way I can use Eclipse to edit, compile, and run them without putting them into a project? Technically, I could probably do the latter two from terminal, but I was wondering if there's a way to do it in the IDE.