Comment 20 for bug 49068

> That doesn't quite make sense. Java may have its own copy of the
> timezone database, but it must use something from the user or system to
> determine the timezone on the machine where it is running.

It makes sense if you consider that jvm's run on many platforms that handle timezone information in their own way. Perhaps there are individual java classes/methods that use the host o/s timezone environment. From what I am seeing in that Sun FAQ, you can't depend on that, which is why they provide the tzupdater tool. Basically the embed a local copy of the official timezone database. You also have to consider that there might be multiple copies of jre/jdk's running on individual machines.

All I know is that even after successfully updating my timezone database java was still not functioning correctly, I have to run the tzupdater tool every time.