I'm trying to create a launcher for Minecraft, but in order to make a proper working launcher I need to have OpenJDK Java 7 set as the default application for opening the .jar file. Here's the problem: when I look at the Open With tab of its Properties window, there's no way to select OpenJDK. What do?
I think this might be a better explanation, if you haven't already found it yourself.
Open a terminal window and type:
Now follow the Step #4 of this answer onward!
All the file associations are stored in the file :
see here for instructions : link
change the line at the beginning of the file