iter = callbacks.iterator();
iter = cb.iterator();
   public void prepare() throws Exception   {      if (trace) { log.trace("executing before prepare hooks " + this); }      Iterator iter = callbacks.iterator();            while (iter.hasNext())      {         TxCallback callback = (TxCallback)iter.next();                  callback.beforePrepare();      }            state = STATE_PREPARED;            if (trace) { log.trace("prepared " + this); }            iter = callbacks.iterator();            if (trace) { log.trace("executing after prepare hooks " + this); }            while (iter.hasNext())      {         TxCallback callback = (TxCallback)iter.next();                  callback.afterPrepare();      }                        if (trace) { log.trace("prepare process complete " + this); }   }