Question

I have an array of valid date formats I want to detect in a some text a user enters:

public static final DateFormat[] DATE_FORMATS = {
    new SimpleDateFormat("M/d/yy"),
    new SimpleDateFormat("M.d.yy"),
    new SimpleDateFormat("M-d-yy"),
    new SimpleDateFormat("M/d/yyyy"),
    new SimpleDateFormat("M.d.yyyy"),
    new SimpleDateFormat("M-d-yyyy"),
    new SimpleDateFormat("M/dd/yy"),
    new SimpleDateFormat("M.dd.yy"),
    new SimpleDateFormat("M-dd-yy"),
    new SimpleDateFormat("M/dd/yyyy"),
    new SimpleDateFormat("M.dd.yyyy"),
    new SimpleDateFormat("M-dd-yyyy"),
    new SimpleDateFormat("MM/d/yy"),
    new SimpleDateFormat("MM.d.yy"),
    new SimpleDateFormat("MM-d-yy"),
    new SimpleDateFormat("MM/d/yyyy"),
    new SimpleDateFormat("MM.d.yyyy"),
    new SimpleDateFormat("MM-d-yyyy"),
    new SimpleDateFormat("MM/dd/yy"),
    new SimpleDateFormat("MM.dd.yy"),
    new SimpleDateFormat("MM-dd-yy"),
    new SimpleDateFormat("MM/dd/yyyy"),
    new SimpleDateFormat("MM.dd.yyyy"),
    new SimpleDateFormat("MM-dd-yyyy"),
    new SimpleDateFormat("yyyy/MM/dd"),
    new SimpleDateFormat("yyyy.MM.dd"),
    new SimpleDateFormat("yyyy-MM-dd")
};

Dates are detected through the code below. this.searchTokens is an array of each search term from the user’s entered text.

    List<Date> datesFound = new ArrayList<Date>();

    for (String token : this.searchTokens) {

        Date date;

        for (DateFormat dateFormat : DateHelper.DATE_FORMATS) {
            try {
                // Attempt to parse this token as a date.
                date = (Date) dateFormat.parse(token);
                datesFound.add(date);
                break;
            } catch (ParseException e) {
                continue;
            }
        }
    }

This code validates and adds the correct dates to my List object for any date except dates formatted like so:

• yyyy/MM/dd
• yyyy.MM.dd
• yyyy-MM-dd

In one of my unit tests, the dates 2010/08/15 and 2011/08/15 match to M/d/yy the first time through the loop and become Date objects with the values Jun 8, 2182 and Jul 8, 2182, respectively. Why would the first SimpleDateFormat in DATE_FORMATS accept a match like this? The number of digits don’t even match up… Is there a better way I should go about detecting these dates?

Answer 1

Call .setLenient(false) on the SimpleDateFormat object you created.

I think M and MM will still both match 1 or 2 digits though. I think you would have to check that yourself (with a regex) if that’s not what you want.