Local Date to UTC conversion

Question

I'm trying to convert system local date to UTC. Below is my code and it looks working for MST and EST formats. But, it is not working as expected.

        String inputDate = "Wed Apr 13 04:00:00 IST 2022";
        SimpleDateFormat sdf = new SimpleDateFormat("EEE MMM dd HH:mm:ss zzz yyyy");
        Date date = sdf.parse(inputDate);
        DateFormat formatUTC = new SimpleDateFormat("MM/dd/yyyy");
        formatUTC.setTimeZone(TimeZone.getTimeZone("UTC"));
        String result = formatUTC.format(date); 
        System.out.print(result); // 04/13/2022

I see that IST zone is 5hrs 30mins ahead from the UTC universal time. So, I should get 04/12/2022 for the given input. But, getting 04/13/2022. what am I doing wrong here? Please advise.

Print out the complete date ***and time*** to see what is happening. — Jim Garrison, Apr 13 '22 at 01:58
`SimpleDateFormat`, oh these classes need to go and die - seriously though, use the `java.time` APIs, save your sanity — MadProgrammer, Apr 13 '22 at 02:26
Learner I can understand how some programmers who learned Java in the last millennium have learned `SimpleDateFormat` and `Date`. If *Learner* implies you are learning Java after 2014, you are learning the wrong thing. You need to learn [java.time, the modern Java date and time API](https://docs.oracle.com/javase/tutorial/datetime/index.html) already mentioned by @MadProgrammer. — Ole V.V., Apr 13 '22 at 03:49
*I see that IST zone is 5hrs 30mins ahead from the UTC universal time.* It depends on whether you understand IST as Irish Summer Time, Israel Standard Time, India Standard Time or something else. How your `SimpleDateFormat` understood it I cannot tell. Three letter time zone abbreviations are generally ambiguous. Avoid relying om them. MST and EST are ambiguous too, so I cannot tell how those were interpreted either. — Ole V.V., Apr 13 '22 at 03:53
The solution to your unexpected result is in my answer here: [how convert date" formate including IST](https://stackoverflow.com/a/66516212/5772882). And also [here](https://stackoverflow.com/questions/57733849/ist-mapped-to-wrong-zoneid-in-java-time-library). Do they answer your question? — Ole V.V., Apr 13 '22 at 04:05
A close vote? This question already contains desired behaviour (`04/12/2022`), a specific problem (undesired output `04/13/2022`) and the shortest code to reproduce. There’s nothing missing. It additionally shows research effort (tried with MST and EST). It’s a good question. If to close, then as a duplicate, not because of missing debugging details because it isn’t missing any. — Ole V.V., Apr 13 '22 at 04:32

score 0 · Answer 1 · answered Apr 13 '22 at 03:36

Try setting the timezone for inputDate as well. Try the below code:

        String inputDate = "Wed Apr 13 04:00:00 IST 2022";
        SimpleDateFormat sdf = new SimpleDateFormat("EEE MMM dd HH:mm:ss zzz yyyy");
        sdf.setTimeZone(TimeZone.getTimeZone("Asia/Kolkata"));
        Date date = sdf.parse(inputDate);
        DateFormat formatUTC = new SimpleDateFormat("MM/dd/yyyy");
        formatUTC.setTimeZone(TimeZone.getTimeZone("UTC"));
        String result = formatUTC.format(date);
        System.out.print(result);

Take a look at this answer.

Local Date to UTC conversion

1 Answers1