Converting ISO8601-compliant String to java.util.Date

Question

solved, see answer below

Hi,

I am trying to convert an ISO8601 formatted String to a java.util.Date. I found the pattern "yyyy-MM-dd'T'HH:mm:ssZ" to be ISO8601-compliant if used with a Locale (compare sample). However, using the java.text.SimpleDateFormat, I cannot convert the correctly formatted String "2010-01-01T12:00:00+01:00". I have to convert it first to "2010-01-01T12:00:00+0100", without the colon. So, the current solution is

SimpleDateFormat ISO8601DATEFORMAT = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ", Locale.GERMANY);
String date = "2010-01-01T12:00:00+01:00".replaceAll("\\+0([0-9]){1}\\:00", "+0$100");
System.out.println(ISO8601DATEFORMAT.parse(date));

which obviously isn't that nice. Am I missing something or is there a better solution?

answer

Thanks to JuanZe's comment, I found the JodaTime-magic, it is also described here. So, the solution is

DateTimeFormatter parser2 = ISODateTimeFormat.dateTimeNoMillis();
String jtdate = "2010-01-01T12:00:00+01:00";
System.out.println(parser2.parseDateTime(jtdate));

To me, this is nice.

Answer 1

Unfortunately, the time zone formats available to SimpleDateFormat are not ISO8601 compliant. SimpleDateFormat understands time zone strings like "GMT+01:00" or "+0100", the latter according to RFC822.

Reformatting your input string using regexp is certainly one possibility, but the replacement rules are not as simple as in your question:

• Some time zones are not full hours off UTC, so the string does not necessarily end with ":00".
• ISO8601 allows only the number of hours to be included in the time zone, so "+01" is equivalent to "+01:00"
• ISO8601 allows the usage of "Z" to indicate UTC instead of "+00:00".

The easier solution is possibly to use the data type converter in JAXB, since JAXB must be able to parse ISO8601 date string according to the XML Schema specification. javax.xml.bind.DatatypeConverter.parseDateTime("2010-01-01T12:00:00Z") will give you a Calendar object and you can simply use getTime() on it, if you need a Date object.

You could probably use JoDa as well, but I don't know why you should bother with that.