Closing a Web Page

Here is part of my code:

if(s.equals("Fluff")){
             Desktop c=Desktop.getDesktop();
             c.browse(new URI("https://www.youtube.com/watch?v=_9kdZ07BCFQ"));
         }

I'd like for the user to be able to type 'stop' to kill the web page. I have looked online, but all I am seeing is window.close(). I tried it, but it didn't work - I think because I am using Desktop instead of window. How would I go about doing this?

I'm new to coding, so the solution may be obvious, I just don't see it. Explain thoroughly - I'd like to learn, not copy/paste.