I don't think you can call a particular thread like that. If you call notify(), you call one thread, selected non-deterministically. If you call notifyAll() you can wake any because all threads are notified.
I think this question too difficult for "beginning" so I shall move it.
Have volatile boolean variables for each Thread and set to true the one for the required Thread. Within the Thread check if its volatile variable is set to true, if so do the needful, if not go back to sleep. Call notifyAll().