Re: Null pointer exception problem
Lew wrote:
Also, all the methods in Vector and Hashtable are synchronized, an
overhead not needed in thread-local contexts. Furthermore, the
Collections class can make synchronized versions of any collection.
Chris Uppal wrote:
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.
Wow. Thank you for this information.
You have thrown petrol on the fire of my contempt for Vector and Hashtable.
--
Lew