You can also use SimpleDateFormat, as in DateTimeFormat
Date startDate = null;
Date endDate = null;
try {
if (validDateStart!= null) startDate = new SimpleDateFormat("MM/dd/yyyy HH:mm", Locale.ENGLISH).parse(validDateStart + " " + validDateStartTime);
if (validDateEnd!= null) endDate = new SimpleDateFormat("MM/dd/yyyy HH:mm", Locale.ENGLISH).parse(validDateEnd + " " + validDateEndTime);
} catch (ParseException e) {
e.printStackTrace();
}