Re: Null pointer exception problem

Unfortunately, that's not quite true. /Some/ of the methods in Vector
and Hashtable are synchronised, including all the methods from "classic"
Vector and Hashtable. But the methods which they gained as part of the
retrofitting to the Collections framework (the ones inherited unaltered from
AbstractList and Dictionary) are not explicitly synchronised, and are not always safe.
Worse, there is no way of telling which of the "new" methods are safe except by
inspecting the sources to java.util.*. Similarly, there is no way of
telling, just from reading code which uses a Vector or Hashtable, whether it is
using methods from the safe "classic" set or from the potentially unsafe new
Collections set.