Hmmm, in thinking about it, I realized that I have over-engineered a solution (albeit my solution is way more powerful than what you are trying to do, and can be used as the stepping stones to wonderful stuff).
Anyway - it looks like you have been ignoring the results of the Runtime.getRuntime().exec() method - it returns a Process, which will allow you to look at the standard input, output, and error for the process you spawned. Had you looked at these,
you should have been able to see the errors, which would have given clues as to the problem.
To start with, you don't need (or want) the dollar sign ($) in your command. You do not put the greater-than symbol (>) in the Microsoft equivalent, so why have it here?
The second thing is that there is no path defined in your process. The exec method allows parameters where you can define your path, or you could list it explicitly.
Combining those two, a simple solution might be: