code: public static long getHoursDifference(Date startDate, Date endDate) {
  		long startTime = startDate.getTime();
  		long endTime = endDate.getTime();
  		long diffTime = endTime - startTime;
  		long diffInHours = TimeUnit.MILLISECONDS.toHours(diffTime);
  		return diffInHours;
  	}
docs: Gets the hours difference.
  
  @param startDate the start date
  @param endDate   the end date
  @return the hours difference