public class Middleman extends Thread {
   private QBuffer in, out;
   private Person p;
   private boolean done;

   // constructor: initializes queue references and exit flag
   public Middleman (QBuffer b1, QBuffer b2) {
      // the parameters b1 and b2 are pointers to input and output queues
      in = b1;
      out = b2; 
      done = false;
   }

   // get items from in queue, reduce by 10 pounds, send to out queue
   // quit when the Go Away message is spotted
   public void run () {
      while (! done) {
         if (! in.isEmpty() && ! out.isFull()) {
            p = (Person) in.dequeue();
            p.setWeight(p.getWeight() - 10);
            out.enqueue(p);
            if (p.getName().compareTo("Go Away") == 0) 
               done=true;
         }
         else {
           yield();
         }
      }
      System.out.println("Middleman is done");
   }
}