openjdk and java runtime?

So I want to get java working in firefox 64 bit. I guess in order to do this I need two javajdk packages installed.

My question is if I do install these two javajdk packages do I still need the javaruntime package installed?

If you don’t plan on doing any development in java, you want the runtime packages (JRE) but not the development ones (JDK).

But from what I have read the regular runtime does not work in when viewing pages in firefox 64 bit with java applets. Is this not the case?

You need the runtime and the plugin.