openjdk and a jar file

[dennislarge]

Most all my Linux knowledge is server-side cli, so not good at troubleshooting desktop stuff. A site I use has a custom launcher jar file for modded Minecraft. Have used it for a couple of years on Windows with no issues. On 22.04 with Gnome, installed opendk-11 and used that as the RunWith, ran fine. Not so good on Numbat Kubuntu. I can manage to start the launcher in Konsole, but not launch any of the options. I think I played with "export DISPLAY=:0.0" to get that far.

Exception in thread "main" java.lang.ClassCastException: class jdk.internal.loader.ClassLoaders$AppClassLoader cannot be cast to class java.net.URLClassLoader

What's new that I need/different to learn about? Besides the whole Xwin environment of course.

[Schwarzer Kater]

Welcome.

So did your .jar run with Kubuntu 22.04 LTS? Did you use Wayland ot X11 in Ubuntu (GNOME) 22.04 LTS? Did you install similar openjdk packages in 22.04 and 24.04?

PS:
I just had a look - *Ubuntu 24.04 LTS uses openjdk 11.0.23, previous *Ubuntu versions (20.04, 22.04 & 23.10) use openjdk 11.0.22. Perhaps there was a small change from 11.0.22 to 11.0.23 that effects your .jar?

[dennislarge]

Thanks for the response. I don't think that minor java diff would matter, but worth trying something.
I think 22.04 used X11, vs the Wayland that I read was default for 24.04. The Linux gui is what I'm probably weakest on.
Been on the road, will have to play more when I get home tomorrow.
Thanks again.