Oh hah hah this is a great question for us game developers. Typical Java recommendation is to make break points but that is super annoying if it's something that happens every frame. You don't really want to have to unpause every millisecond. Did you know that you can configure breakpoints to not pause in Idea? That's super cool. That way you can log different stuff without having to recompile.
But in all honesty soutv is an incredible shortcut and I usually debug that way...