Convertion of DateTimeFormat in java!

Question

I just need a small help regarding the DateTime format in java.I am writing a simple chat application based on yahoo messanger,in which I will read the packet of yahoo messanger and display the chat messages.Now I want to display the time from the given header.In a particular article it is said the "timestamp" will be 0x477BBA61(decimal 1199290977) which means "Wed, 2 Jan 2008 16:22:57 GMT" . I am trying to reveal how that decimal is converted to that particular date.I tried to write a simple java application to convert that and its giving some other time.

  public static void main(String[] arg)
        {
             Calendar  obj = Calendar.getInstance();
          obj.setTimeZone(TimeZone.getTimeZone("GMT"));
            obj.setTimeInMillis(1199290977l);
          System.out.println( obj.get(Calendar.HOUR)+":"+obj.get(Calendar.MINUTE));
        }

output:9:8

Can anybody help me with this?

In your code, you have 11992909771 (which is different to your decimal value on your question). — Buhake Sindi, Apr 14 '11 at 08:49
@The Elite Gentleman: its 1199290977l the last one is "l" not "1". — Harry Joy, Apr 14 '11 at 08:50
@dogbane ::Article Link:http://sec.drorshalev.com/dev/yahoo/Yahoo!AuthenticationSchemes.htm — kiddo, Apr 14 '11 at 08:52
@kiddo: This confusion is why it's better to use "L" than "l". — Jon Skeet, Apr 14 '11 at 08:52
@kiddo: I've made it a habit to use a capital `L` for the `long`-postfix, because not everyone uses a font where `1` and `l` are easy to distinguish. — Joachim Sauer, Apr 14 '11 at 08:53
@kiddo The article says that the timestamp is "the number of SECONDS elapsed since 1-1-1970". Java dates are represented in millis so you need to convert. — dogbane, Apr 14 '11 at 08:56
@kiddo, from the iPad, that `l` looks like a `1`, and my post was posted from the iPad. — Buhake Sindi, Apr 14 '11 at 09:31

score 4 · Accepted Answer · answered Apr 14 '11 at 08:48

Your value of 1199290977L is wrong. That's measuring in seconds since the Unix epoch (midnight on January 1st 1970 UTC) - you need to multiply it by 1000 to get milliseconds since the epoch.

You're also using Calendar.HOUR which is the 12-hour clock instead of Calendar.HOUR_OF_DAY which is the 24-hour clock. This code:

Calendar  obj = Calendar.getInstance();
obj.setTimeZone(TimeZone.getTimeZone("GMT"));
obj.setTimeInMillis(1199290977000L);
System.out.println(obj.get(Calendar.HOUR_OF_DAY) + ":" + 
                   obj.get(Calendar.MINUTE));

... prints 16:22.

However, you should definitely use the java.text.DateTimeFormat class instead of doing this yourself - or, ideally, use Joda Time instead.

You are right Jon,thanks for your help.I really appreciate it.It saved my time. — kiddo, Apr 14 '11 at 08:55

score 0 · Answer 2 · answered Apr 14 '11 at 08:50

0

Imho to proceed you need to know:

whether or not that number is milliseconds or not
what is the starting point (in java is  January 1, 1970, 00:00:00 GMT)

answered Apr 14 '11 at 08:50

Riccardo Cossu

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score 0 · Answer 3 · answered Apr 14 '11 at 09:07

0

The timezone is probably in seconds; try to multiply the value by 1000 to get the milliseconds which Calendar expects.

answered Apr 14 '11 at 09:07

Aaron Digulla

297,790
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qwerty · Answer 4 · 2011-04-14T08:53:14.150

-2

You need to use a SimpleDateFormat - look at the documentation, it is pretty easy to understand, plus it includes a lot of examples (so you don't need to search for "date format tutorial" or something like that :))

EDIT: Ooops, I missed the part where you are passing the time in seconds instead of milliseconds and the result time is wrong, I misinterpreted your question and thought that you want to just parse the time, Jon's answer is better :)

edited Apr 14 '11 at 08:53

answered Apr 14 '11 at 08:43

qwerty

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I didn't downvote, but it doesn't really answer the question. It doesn't explain why the current code gives the result it does. – Jon Skeet Apr 14 '11 at 08:51
@Jon - yes, I read your answer and saw what is wrong here, I didn't saw what exactly he wants (and I edited my answer). I guess I shouldn't answer on SO when I am toasted. – qwerty Apr 14 '11 at 08:54
@The toasted as in made a mistake because I am tired, apologized for it and really don't feel like explaining myself that much over it – qwerty Apr 14 '11 at 09:41

Convertion of DateTimeFormat in java!

4 Answers4