public synchronized String generateId(){
  StringBuilder sb=new StringBuilder(length);
  sb.append(seed);
  sb.append(sequence.getAndIncrement());
  return sb.toString();
}

public synchronized String generateId ( ) { StringBuilder sb = new StringBuilder ( length ) ; sb . append ( seed ) ; sb . append ( sequence . getAndIncrement ( ) ) ; return sb . toString ( ) ; }
generate a unique id
