code: private long findInterval(final String dateFormat) {
  
  		final long max = TimeUnit.DAYS.toMillis(365);
  		final long step = TimeUnit.SECONDS.toMillis(60);
  
  		try {
  
  			final SimpleDateFormat format = new SimpleDateFormat(dateFormat);
  			final long initial = format.parse(format.format(3600)).getTime();
  
  			for (long i = initial; i < max; i += step) {
  
  				final long current = format.parse(format.format(i)).getTime();
  
  				if (initial != current) {
  					return i - initial;
  				}
  			}
  
  			return max;
  
  		} catch (ParseException pex) {
  			logger.warn("", pex);
  		}
  
  		return max;
  	}
docs: This method takes a date format and finds the time interval that it
  represents.