[Incidentally don't use Vectors if you can help it, they are more or less deprecated]
But all this means is that multiple threads will not corrupt the data within the Collection. ie when a thread puts something at index 12 then that is where it goes. This guarantee does not hold for a plain List. The upshot is that there is a big performance gain in regular Lists when concurrency isn't an issue.
However you must still ensure that the code that uses a thread-safe Collection is thread-safe itself. It doesn't have magic powers!
does that look thread-safe, whatever the flavour of the List?
SCJP 1.4, SCJD
What are you doing? You are supposed to be reading this tiny ad!
the new thread boost feature brings a LOT of attention to your favorite threads