getting java .jar program to run, even in terminal in Neon

[pwrcul]

I am trying to run a free, graphically pleasing analysis tool called VOSviewer as a JRE. (Info on it is at https://www.vosviewer.com/)
It never gets going on my laptop, and I am not sure what to tweak to get it to work.
It is working great on my desktop.
Both are running KDE Neon, based on Ubuntu 18.04.
I have both Oracle java 12.0.2 and openjdk 11 runtime with Oracle 12 as the default.
I see the logo of each a short while when I try to start VOSviewer.jar but java silently fails.
I checked and see I have default-jre installed.

I looked into /etc/ for their components and found nothing obvious.
I tried to get a verbose account by using the command line to get java starting up in the terminal, but I am not expert enough to force it to access and run the .jar in the same directory.

Here's a recent attempt:
jim@tabby6:~/Downloads/VOSviewer$ java -jar VOSviewer.jar
Error: Unable to access jarfile VOSviewer.jar
jim@tabby6:~/Downloads/VOSviewer$ ls
data HISTORY.txt LICENSE.txt Manual_VOSviewer_1.6.11.pdf VOSviewer.jar

I would appreciate your suggestions and alternatives.

[Don B. Cilly]

Long shot, but, maybe a simple permissions issue?
instead of ls, try ll.

[pwrcul]

Thank you, Don B. Cilly,
On the desktop advanced permissions are r-x for owner, group, others.
On the laptop for VOSviewer.jar advanced permissions I changed them to match by adding read for owner and it now works. Amazing, if that is what did the trick.
Thanks for the suggestion. I am in business.

Now how do I change the control buttons readability for a high DPI screen... for both VOSviewer and Pajek which is running under wine, so one a .jar and the other Windows and apparently not under control of Plasma's System Settings? I guess that will be a Plasma question.

[Don B. Cilly]

Well, if you had to change them to read for owner... I mean, if the owner didn't have read permission, it would give "Unable to access jarfile", right?

So I guess that is what did the trick.

[pwrcul]

I set to rwx for all and I can start VOSviewer in the terminal.

But the workaround for HiDPI screens is not working.
java -Dsun.java2d.uiScale=2 -jar VOSviewer.jar
starts the program but the buttons, etc. are not really readable.

[pwrcul]

I set to rwx for all and I can start VOSviewer in the terminal.

But the workaround for HiDPI screens is not working.
java -Dsun.java2d.uiScale=2 -jar VOSviewer.jar
starts the program but the buttons, etc. are not really readable.

[pwrcul]

I heard back from a co-developer of VOSviewer that they hope to have a fix before the end of the year.

I will live with it since I can figure out the buttons on the desktop and enjoy the high resolution of the laptop...