/**
         * Searches the current list for a given topic.
         *
         * @param topic
         *            The topic the list shall be searched for. It is assumed
         *            that the given topic is not null.
         * @return
         */
        public InterestListElem searchInterest(Topic topic) {
            InterestListElem currentElem = this;
            do {
                if (currentElem.getInterest() == topic) {
                    return currentElem;
                }
                currentElem = currentElem.getNext();
            } while (currentElem.getNext() != null);
            return null;
        }