code: private static String trySkip(StringTokenizer st, String s1, Calendar cal) {
  		while (true) {
  			TimeZone tz = timeZoneMapping.get(s1);
  			if (tz != null) {
  				cal.setTimeZone(tz);
  				if (!st.hasMoreTokens())
  					return null;
  				s1 = st.nextToken();
  				continue;
  			}
  			if (voidData.contains(s1)) {
  				if (s1.equalsIgnoreCase("pm"))
  					cal.add(Calendar.AM_PM, Calendar.PM);
  				if (s1.equalsIgnoreCase("am"))
  					cal.add(Calendar.AM_PM, Calendar.AM);
  				if (!st.hasMoreTokens())
  					return null;
  				s1 = st.nextToken();
  				continue;
  			}
  			return s1;
  		}
  	}
docs: Handle some Date Keyword like PST UTC am pm ...
  @param st
  @param s1
  @param cal
  @return