public Date tryToParse(String dateString) {
        // Java doesn't like timezones in the form ss+hh:mm
        // It only likes the hhmm form, without the colon
        int n = dateString.length();
        if (dateString.charAt(n - 3) == ':' &&
                (dateString.charAt(n - 6) == '+' || dateString.charAt(n - 6) == '-')) {
            dateString = dateString.substring(0, n - 3) + dateString.substring(n - 2);
        }

        for (DateFormat df : iso8601InputFormats) {
            try {
                return df.parse(dateString);
            } catch (java.text.ParseException e) {
                //swallow
            }
        }
        return null;
    }
Tries to parse the date string; returns null if no parse was possible.
<p>
This is not thread safe!  Wrap in synchronized or create new {@link DateUtils}
for each class.

@param dateString
@return
tika-core/src/main/java/org/apache/tika/utils/DateUtils.java