I see the question is old. But I used the DateUtils static methods ceiling and truncate. Came in pretty handy instead of using multiple lines of code.
Date today = new Date();
DateUtils.truncate(new Date(), Calendar.MONTH) // Thu Dec 01 00:00:00 EET 2016
DateUtils.ceiling(new Date(), Calendar.MONTH) // Sun Jan 01 00:00:00 EET 2017