Q: "if you want to use java command tool, you must install the JDK" .

I just started using a Mac at my broadcast studio that I'd never used before.  Doing the same thing.  Did what several folks said to do, still pops up.  Am researching with a friend who is an Apple engineer.  Will post later today when we find an answer.

thank you very much for your help BenB

I haven't tried this yet, but will when I get to my work computer tomorrow.  It seems there some old 32-bit application running your Mac, that insists on using an outdated version of Java.  Unless you know what the app is, and can remove or update it, here's what you need to install.  I will be installing this tomorrow, will post my results back then.

Download Java for OS X 2015-001

I'm looking forward for your answer BenB.

I found this Apple knowledge base article.  I installed the old version 6 thingy, and so far today I've not seen that stupid message pop up.

https://support.apple.com/kb/DL1572?locale=en_US