Could this be a no thread safe problem?

Hello!

We are running some prestanda-test right now.
We try to stress our application.

We saw some "strange" errors due.

ArrayOutOfBoundsException.

In a method looking pretty like this, (home right now, code is at work)

public static String formatStringToDate(String input)
{
  ... some code...
  return YYYYMMDD.format(); //Exception at this line
}

YYYYMMDD is if not wrong SimpleDateFormat.

How ever we got some, perhaps 4, ArrayOutOfBoundsException 46, ArrayOutOfBoundsException -16 etc.

...after 5000 requests through JBossWS down to this DateUtil class.

All the time the method got the parameter set to the same value, like "2010-10-08".

Since we just got a few errors and the calls got the same parameters, I started to think that this problem might depend on thread safety, or I'm I wrong?

Is it possible that several threads access this method at the same time and screw up each others calls?

Best regards
Fredrik