SimpleDateFormat dateFormatter = new SimpleDateFormat ("yyyyMMdd", Locale.KOREA);
Date date1 = dateFormatter.parse("20110101");
Date date2 = dateFormatter.parse("20111231");
System.out.println(String.format("%d", ( date2.getTime() - date1.getTime() ) / ( 1000 * 60 * 60 *24 ));