Question

My controller recieves this String “20120115Z” as a @RequestParam, representing a date.

I would like to transform it to this format: yyyy-MM-dd, so I would have a new string like this 2012-01-15.

As you can see, there’s no delimiters, only the ‘Z’ always as the last character.

My approach was pretty obvious:

String data = 
strData.substring(0, 4) + "-" + 
strData.substring(4, 6) + "-" + 
strData.substring(6, 8);

And it works, but as you know these “magic numbers” are something to avoid. I also tried to use a a regular expression like “^[^\s]{4}[^\s]{2}[^\s]{2}Z$”, but without success.

Any idea?

UPDATE: Finally I’ve done it with Joda-Time DateTime class as @Brian Agnew suggested

DateTimeFormatter fmt = DateTimeFormat.forPattern("YYYYMMdd'T'hhmm'Z'");
String strData = "20120115T0600Z";
DateTime dt = fmt.parseDateTime(strData);

printing method:

private static void printDateTime(DateTime dt) {
    int year = dt.getYear();
    int month = dt.getMonthOfYear();
    int day = dt.getDayOfMonth();
    int hour = dt.getHourOfDay();
    int minute = dt.getMinuteOfHour();
    int second = dt.getSecondOfMinute();
    int millis = dt.getMillisOfSecond();
    String zone = dt.getZone().toString();
    log.info("fecha: "
            + day + "/" + month + "/" + year + " " + hour + ":" + minute + ":" + second + ":" + millis
            + " " + zone + "\n");
}

Output

15/1/2012 6:0:0:0 UTC

Thanks everyone

Answer 1

I would perhaps use a Joda-Time DateTimeFormat.

Why ? It’ll check the format, including valid values for hours/minutes/seconds, and give you back a suitable DateTime object which you can do what with (including reformat it using a similar approach).

You simply give it the format that you want to parse and it’ll do all the rest. You have a date, so treat it as such.