Candy,
If it's not clear yet, the difficulty in trying to answer your question is that most Ranchers likely have little idea what a LimitedTextContainer is.
Google doesn't even know.
Regarding your question whether you "need something in the ()", it depends. The somethings in the () are also referred to as method arguments.
I'm afraid I haven't a good clue as to what the transferFocus method does or what a LimitedTextContainer might be. Where did you get this LimitedTextContainer class?