[LANG-1219] FastDateFormat doesn't respect summer daylight in localized strings

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.4
• Fix Version/s: 3.5
• Component/s: lang.time.*
• Labels: timezone
• Flags: Important
• Assignee: Charles Honton
• Reporter: Jarek
• Created: 21/Apr/16 14:09
• Updated: 19/Oct/16 07:00
• Resolved: 23/Apr/16 20:04

Description

FastDateFormat can't properly parse dates with daylight saving in the "z" pattern. It always returns date without daylight saving. Test case:

		SimpleDateFormat format = new SimpleDateFormat("dd.MM.yyyy HH:mm:ss z", Locale.GERMANY);
		Date d1 = format.parse("26.10.2014 02:00:00 MESZ");
		Date d2 = format.parse("26.10.2014 02:00:00 MEZ");
		System.out.println(d1);
		System.out.println(d2);
		FastDateFormat formatt = FastDateFormat.getInstance("dd.MM.yyyy HH:mm:ss z", Locale.GERMANY);
		Date d3 = formatt.parse("26.10.2014 02:00:00 MESZ");
		Date d4 = formatt.parse("26.10.2014 02:00:00 MEZ");
		System.out.println(d3);
		System.out.println(d4);	

returns:
SDF: Sun Oct 26 02:00:00 CEST 2014
SDF: Sun Oct 26 02:00:00 CET 2014
FDF: Sun Oct 26 02:00:00 CET 2014
FDF: Sun Oct 26 02:00:00 CET 2014

FastDateFormat returns the same date, which is wrong.

Bug is in the FastDateParser.TimeZoneStrategy.setCalendar:

@Override
        void setCalendar(final FastDateParser parser, final Calendar cal, final String value) {
            TimeZone tz;
            if(value.charAt(0)=='+' || value.charAt(0)=='-') {
                tz= TimeZone.getTimeZone("GMT"+value);
            }
            else if(value.startsWith("GMT")) {
                tz= TimeZone.getTimeZone(value);
            }
            else {
                tz= tzNames.get(value);
                if(tz==null) {
                    throw new IllegalArgumentException(value + " is not a supported timezone name");
                }
            }
            cal.setTimeZone(tz);
        }

It's not enough to just call: cal.setTimeZone.
If zone names in standard and daylight time are different, you have to check the name in DateFormatSymbols.getInstance(locale).getZoneStrings(); and if it's >= 3, you have to activate daylight mode.Just like SimpleDateFormat does it:

1491            // (abbreviation) for both standard and daylight time,
1492            // let the time zone in the Calendar decide which one.
1493            if (!useSameName) {
1494                calendar.set(Calendar.ZONE_OFFSET, tz.getRawOffset());
1495                calendar.set(Calendar.DST_OFFSET,
1496                             j >= 3 ? tz.getDSTSavings() : 0);
1497            }