Oh, look, there's already an antique jre installed on my os, not compatible with the particular jre needed by this application, which I first need to uninstall.

Oh, look, there's already an antique jre installed on my os, not compatible with the particular jre needed by this application, which I first need to uninstall. And then hope that it doesn't break anything else in the process, because I haven't been following the minutae of java development environments for the last n+1 years... I think it falls solidly in the "easy if you know it, and a wasted q hours if you don't" category.