On LXLE I could not run a .jar file with OpenJDK java 8 runtime.
After a long search I found the problem
In the defaults.list there is a wrong value

Remedy: Edit this file, found under: user/share/applications/
Search for "jar"
You fill find that there is a wrong value in the line
application/x-jar=openjdk-7-java.desktop
It should be
application/x-jar=openjdk-8-java.desktop
Because it is version 8 which is installed not 7
Also in the next line change 7 into 8.
Reboot and the problem is solved