First and foremost -- welcome to JavaRanch!
Next off, I'm not sure exactly what it is that you're asking -- to check if the number is odd? that it's divisible by three? both?
Next, after clarifying your question, what have you tried so far, and how doesn't it work to your satisfaction?
And finally, I'm going to ask that the mods move this
thread to the beginning
Java section as it's not a Swing question.
Much luck, and again, welcome!