Hello,
My primary concern here is setting the default application for handling .jar files to OpenJDK.
I use Linux Mint Debian Edition with LXDE.
When I tried to open a .jar file, it was linked to Eclipse (Java IDE) as the default application. I want to change that to OpenJDK, but it's nowhere to be found in the menus. It's definitely installed though, I checked in Synaptic (and otherwise the .jar file wouldn't be able to run in eclipse either, right?).
How can I make OpenJDK available in the menu?
Since the standard way of doing this is unavailable, is there a CL tool for assigning default applications to file extensions? What command would I have to use for this specific binding (bcs I'm not very good at making the glyphs in your standard man page into a functioning command, I always get it wrong...)?
Thanks, Ben

in gnome you can right click on file, select properties and there is a tab "open with". but I do not know what kind of GUI you use.

As stated in my avatar and first post, my desktop is LXDE.
In LXDE, you do it the same way: right click, "open with" and you get to chose the application to open it with, and the option to make that the default for this file type by checking the box.
That choice, however, is limited to applications listed in the applications menu. in my case, OpenJDK is NOT LISTED THERE, so I don't get to choose it.
there is also the option to provide a command with path to the executable, which I tried, but didn't work.
Hence my question about a CL tool and possible command to use it with.

If OpenJDK is not on your applications menu, add it to your applications menu

I think this should work:

Look in your /usr/share/applications
You should find a couple of OpenJDK *.desktop files
Copy those into your ~/.local/share/applications folder
(You may have to change ownership and permissions)
That should make OpenJDK magically appear on your applications list.