6 
String date = jsonobject.getString("needbydate");
DateFormat df = new SimpleDateFormat("MMM/dd/yyyy");
DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'hh:mm:ssZ");
Date startDate = sdf.parse(date);
String needbydate = df.format(startDate).toString()+"";

What is happening::

  • At the start

date=2014-12-17T21:37:00+00:00

  • At the end

needbydate= Dec/18/2014

17 is changed to 18 .... What wrong am i doing in conversion

EDIT:

            String date=jsonobject.getString("needbydate");
            DateFormat df = new SimpleDateFormat("MMM/dd/yyyy",Locale.ENGLISH);
            DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'hh:mm:ss",Locale.ENGLISH);
            sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
            Date startDate;
            startDate = sdf.parse(date);
            needbydate = df.format(startDate).toString()+"";
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2
  • can you try with HH instead of hh? Capital h is for the 24hours format Commented Dec 17, 2014 at 11:17
  • 1
    I am getting the 17th fine but I have no Z on the SDF as it is causing an Unparseable date exception. Commented Dec 17, 2014 at 11:26

3 Answers 3

Reset to default
6

Your date formats are using the system default time zone. That's okay for your input, because it specifies the UTC offset explicitly - but for your output, you've just got a date. So it's showing you the date that that point in time occurred in your system time zone.

You need to think about what time zone you want it to be - and whether that's affected by a non-zero offset in your input. You can use DateFormat.setTimeZone to set the time zone to be used on output. (For example, should 2014-12-17T21:37:00-05:00 show as December 18th (UTC) or December 17th (source time zone)?)

You should also be using HH in your input format instead of hh, as it's clearly a 24-hour value rather than a 12-hour value.

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5 Comments

Thanks for the input .... Please see the edit .... Is this what you are refering ... I have used jodaLibrary for this ... How can i learn about these conversions any resource(I beginner in this concepts)?
@Devrath: Well no, I never suggested moving to Joda Time, although that's generally better. It's not clear why you're using a specific time zone here, or what's wrong with what I actually suggested. If you do want to use Joda Time, you'd be better off using a DateTimeFormatter for the parsing, instead of passing the string into the constructor.
Oh ... k how to use DateFormat.setTimeZone any sample .... i am not able to read the docs and imprint it (newbie to these concepts )
@Devrath: you call it with the time zone you want the output to use. I don't know what else there is to say...
@Devrath To learn Joda-Time, simply search here on StackOverflow for "joda". You will find hundreds of practical examples. Much easier to learn when you see problem->solution rather than just reading the JavaDoc.
1

With the help of JonSkeet resolved this ... Complete solution ...here

            String date=jsonobject.getString("needbydate");
            DateFormat df = new SimpleDateFormat("MMM/dd/yyyy",Locale.ENGLISH);
            df.setTimeZone(TimeZone.getTimeZone("UTC"));
            DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'hh:mm:ss",Locale.ENGLISH);
            sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
            Date startDate;
            startDate = sdf.parse(date);
            needbydate = df.format(startDate).toString();
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1 Comment

Why the concatenation of an empty string at the end?
1

Joda-Time

Much easier in Joda-Time indeed. Joda-Time handles that standard ISO 8601 format string by default.

When the input string includes an offset (+00:00 in this case), the rest of the string is parsed accordingly. When passing a time zone object at the same time, Joda-Time adjusts the parsed value to that zone. See the code example below for a demo.

Note how the adjustment for Kolkata India means the date rolls over from the 17th to the 18th.

String input = "2014-12-17T21:37:00+00:00";

DateTimeZone zone = DateTimeZone.forID( "America/Montreal" );
DateTime dateTimeMontréal = new DateTime( input , zone ); // Parse as UTC because of "+00:00" offset, then adjust to desired time zone of Montréal.

Easily adjust to other time zones.

DateTime dateTimeParis = dateTimeMontréal.withZone( DateTimeZone.forID( "Europe/Paris" ) );
DateTime dateTimeUtc = dateTimeMontréal.withZone( DateTimeZone.UTC );
DateTime dateTimeKolkata = dateTimeMontréal.withZone( DateTimeZone.forID( "Asia/Kolkata" ) );

Dump to console.

System.out.println( "input: " + input );
System.out.println( "dateTimeMontréal: " + dateTimeMontréal );
System.out.println( "dateTimeParis: " + dateTimeParis );
System.out.println( "dateTimeUtc: " + dateTimeUtc );
System.out.println( "dateTimeKolkata: " + dateTimeKolkata );

When run.

input: 2014-12-17T21:37:00+00:00
dateTimeMontréal: 2014-12-17T16:37:00.000-05:00
dateTimeParis: 2014-12-17T22:37:00.000+01:00
dateTimeUtc: 2014-12-17T21:37:00.000Z
dateTimeKolkata: 2014-12-18T03:07:00.000+05:30
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