On your way in you may have missed that we have a policy on screen names here at JavaRanch. Basically, it must consist of a first name, a space, and a last name, and not be obviously fictitious. Since yours does not conform with it, please take a moment to change it, which you can do right here.
As to your question, this can be achieved with a mechanisms called LiveConnect. The Applets FAQ has some links on the subject.
Surfs up space ponies, I'm making gravy without this lumpy, tiny ad: