}
                index++;
            }
        }
        return -1;
    }

    @Override
    public void writeExternal(final ObjectOutput s) throws IOException {
        s.writeInt(size);
        for (Entry e = header.next; e != header; e = e.next) {
            s.writeObject(e.element);
        }
    }

    @SuppressWarnings("unchecked")
    @Override