I followed the instructions from here https://en.opensuse.org/SDB:Installing_Java to get Oracle java running because an application I need wouldn't run reliably with openjdk. Once I got it installed (/usr/java/jre1.8.0_152/) I had the problem that the app (a .jnlp file) would seem to start and then java would give an error:
Unable to launch the application.

After playing around with Java permissions with no change in result I thought I would try running the app. as the root user (using Dolphin in root user mode) and sure enough the app. started just fine.

Clearly I should not need to be root user to run applications so does anyone have any idea what I would need to do to make these web Java apps. run as a normal user?