Search:

The command that you want to execute.
If you don't know the command, you should use the Desktop class.

If you want to specify the command to use to open the file,
build a commandline and use the Runtime exec() method to execute it.

What does "run that file" mean?
Are you asking how to ask the OS to start a program when it is given a file to be opened?
See the Desktop class.

Or if you have the full commandline to execute,...