I think the easiest way to tell if something needs Java is to simply try running the program or app. If it needs Java you'll get a prompt. For example, I use Opera as my browser. If I try to access the official US Time website at time<dot>gov I get this prompt. I uninstalled Java bout a year ago and I haven't missed it or needed it.
I'm not aware of any other software that can scan your computer to see if installed programs or apps need Java.