You could try process.destroyForcibly().waitFor().
Why are you catching the IOException at the beginning? I'm assuming that you only want to interact with the process if you've started it successfully.
I'm assuming this is a constructor, because you're adding an action listener to a button in this code. If it is, it's inappropriate to spawn a thread here. In fact, you shouldn't be using a thread at all, you should be using a SwingWorker.