Converting to UTC time zone

[Rajesh Pattabi]

hi i need to convert UTC my code is

   /**
         * This method converts the date in String format to Universal TimeZone,
         * if the to UTC flag is true and returns a String[] with Date and Time
         * in it. If the toUTC is false then
         *
         *
         * @param convertDate
         * @param toUTC
         * @return
         */
        public static String[] convertToUTC(String convertDate , boolean toUTC)
        {
            Calendar tempDate = new GregorianCalendar();
            String[] returnDate = new String[2];
            Date date = null;
            

            Format formatterDate  = new SimpleDateFormat("MM/dd/yyyy");
            DateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy HH:mm");
            Format formatterTime  = new SimpleDateFormat("HH:mm");
            /* TODO The following line is for testing only.
             * TO BE CHANGED TO TIMEZONE.getDefault(); later.
             **/
            TimeZone timeZone = TimeZone.getTimeZone("US/Pacific");
            try
            {
                date = dateFormat.parse(convertDate);
            }
            catch (ParseException parseException)
            {
                Logger.error("Error Occured in validateDisplayPromptScreen Service",
                        parseException,QCRCommonServiceMethods.class);
            }
            
            long offset  = timeZone.getOffset(date.getTime());
            int hrs = (int)((double)offset/(double)(1000*60*60));
            tempDate.setTime(date);

            if(toUTC)
            {
                tempDate.add(Calendar.HOUR,-hrs);
                date = tempDate.getTime();
                returnDate[0] = formatterDate.format(date);
                returnDate[1] = formatterTime.format(date);
            }
            else
            {
                tempDate.add(Calendar.HOUR,hrs);
                date = tempDate.getTime();
                returnDate[0] = dateFormat.format(date);
            }
      

            return returnDate;
        }

this code does not give correct output for input date 03/13/2011 02:00

[Tim Moores]

What is the output? What do you think it should be instead?

[Rajesh Pattabi]

when i give 03/13/2011 08:00........ it should return 03/12/2011 01:00 that is input date -7hrs is correct for UTC conversion but for DST times it converts -8 instead -7.

[Rajesh Pattabi]

Tim Moores,
Actually i am trying to convert date and time to UTC. My client local timezone is US/Pacific. this code works fine for all the cases if i give 03/20/2012 10:00 it converts correctly and returned 03/20/2012 03:00 but for this DST when i give input for 03/13/2011 08:00 it should return 03/12/2011 01:00 but this code returning 03/12/2011 00:00

[Jeff Verdegan]

Rajesh Pattabi wrote:Tim Moores,
Actually i am trying to convert date and time to UTC. My client local timezone is US/Pacific. this code works fine for all the cases if i give 03/20/2012 10:00 it converts correctly and returned 03/20/2012 03:00 but for this DST when i give input for 03/13/2011 08:00 it should return 03/12/2011 01:00 but this code returning 03/12/2011 00:00

That doesn't sound right.

You claim you're going TO UTC FROM US/Pacific. However, when you say "if i give 03/20/2012 10:00 it converts correctly and returned 03/20/2012 03:00", that means you're going the opposite direction from what you're claiming.

And an input of 03/13/2011 08:00 in either TZ is not 03/12/2011 01:00 or 03/12/2011 00:00 as you claim.

The correct way do to this is to simply set the DateFormat's TZ to the one you want to display in. You don't do any conversion math with offsets, and you don't set the Calendar's "hours" field. Note that regardless of which TZ you're using for your display, you're viewing the same instant in time, and hence the same DATE object.