Re: Parsing IETF standard date format.
From: Assafsuf (assaf_at_il.ibm.com)
Date: 12/14/03
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Date: 14 Dec 2003 06:45:34 -0800
"P.Hill" <goodhill@xmission.com> wrote in message news:<bra5op$par$1@terabinaries.xmission.com>...
> Assafsuf wrote:
> > Now, I am trying to use the DateFormat class to parse a string in that format
> > with no luck.
>
> In the future, it would be better if you would define more cleary the term
> "luck". Give an example of what you think is wrong. But in this case, I
> think I know.
>
> > Can anyone post a sample code for that, or show me what is wrong in
> > the code below?
> >
> > SimpleDateFormat formatter = (SimpleDateFormat)DateFormat.getDateInstance();
> > formatter.applyPattern("EEE, d MMM yyyy HH:mm:ss z");
> > Date d = formatter.parse(date);
>
> Nothing is wrong with the code, but I'm sure you then used d.toString()
> to look at the value in d. Dates are binary values. They have no idea
> of Timezones, UNTIL YOU CONVERT IT TO A STRING. at that point it has to
> pick a timezone. In that case it just uses the VM default.
>
> You probably were thinking that a Date internally new about hours, minutes
> and especially a TZ. It is a binary value, that is all.
>
> In the following example, my current default is MST (North American/Denver)
>
> Try this code:
> public class ParseDate {
> public static void main(String[] args) throws ParseException {
> String dateStr = "Thu, 11 Dec 2003 22:13:14 MST";
> SimpleDateFormat formatter =
> (SimpleDateFormat)DateFormat.getDateInstance();
> formatter.applyPattern("EEE, d MMM yyyy HH:mm:ss z");
> Date date = formatter.parse(dateStr);
> System.out.println( date.getTime() + ": date.toString() = " + date +
> " : the original string is: " + dateStr );
>
> dateStr = "Sat, 12 Aug 1995 13:30:00 GMT";
> date = formatter.parse( dateStr );
> System.out.println(
> "The following only differ by the current default timezone.");
> System.out.println( date.getTime() + ": date.toString() = " + date +
> " : the original string is: " + dateStr );
>
> formatter.getCalendar().setTimeZone( TimeZone.getTimeZone( "GMT" ) );
> date = formatter.parse( dateStr );
> System.out.println(
> "After tweeking the timezone in the calendar of the date format then
> parsing and formatting with that.");
> System.out.println( date.getTime() + ": formated " +
> formatter.format(date) + " : the original string is: " + dateStr );
> System.out.println(
> "Notice that the last dates have the same internal binary values.");
> }
> }
>
> Which results in:
> 1071205994000: date.toString() = Thu Dec 11 22:13:14 MST 2003 : the original
> string is: Thu, 11 Dec 2003 22:13:14 MST
> The following only differ by the current default timezone.
> 808234200000: date.toString() = Sat Aug 12 07:30:00 MDT 1995 : the original
> string is: Sat, 12 Aug 1995 13:30:00 GMT
> After tweeking the timezone in the calendar of the date format then parsing and
> formatting with that.
> 808234200000: formated Sat, 12 Aug 1995 13:30:00 GMT : the original string is:
> Sat, 12 Aug 1995 13:30:00 GMT
> Notice that the last dates have the same internal binary values.
>
>
> Now you can begin to understand why Date.parse() is deprecated.
> If all of the Calendar functionality was in Date You'd have to have a way to set
> a Date into a mode where it would be working in a different TZ. All such
> modes would result in a lot of static methods like Date.setToStringTimeZone().
> That is the intent of DateFormat and Calendars. To hold a binary date
> use Date. To break a date into separate fields use a Calendar. To go directly
> to a formatted String us DateFormat.
>
> HTH,
> -Paul
Thanks,
The problem was that I was getting a parse exception if I didn't
specify Locale.english.
Assaf.
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