CODEWITHSUNDEEP
javacalendar
Hey StackExchange
Hey StackExchange

Reputation: 2125

Java: Wrong hour from Calendar instance?

Running :

public class test {
    @Test
    public void displayDate() {
        SimpleDateFormat MONTH_FORMAT = new SimpleDateFormat("MMM", Locale.getDefault());
        String testDateStr = "2017-07-01T07:58:23.000Z";
        Calendar calendar = getFormatedDate(testDateStr);
        int yearInt  = calendar.get(Calendar.YEAR);
        String monthStr = MONTH_FORMAT.format(calendar.getTime()).toUpperCase();
        int monthInt = calendar.get(Calendar.MONTH);
        int dayInt  = calendar.get(Calendar.DAY_OF_MONTH);
        int hour24 = calendar.get(Calendar.HOUR_OF_DAY);
        int min = calendar.get(Calendar.MINUTE);
        int sec = calendar.get(Calendar.SECOND);
        System.out.println(testDateStr);
        System.out.println(String.format("%s-%s-%s %s:%s:%s", yearInt, monthStr, dayInt, hour24, min, sec));
        System.out.println(String.format("%s-%s-%s %s:%s:%s", yearInt, monthInt, dayInt, hour24, min, sec));

    }

    private Calendar getFormatedDate(String dateStr) {
        Instant instant;
        try {
            instant = Instant.parse(dateStr);
        } catch (DateTimeParseException e) {
            e.printStackTrace();
            return null;
        }
        ZonedDateTime zdt = ZonedDateTime.ofInstant(instant, ZoneId.systemDefault());
        Calendar calendar = GregorianCalendar.from(zdt);
        return calendar;
    }
}

I'm getting:

2017-07-01T07:58:23.000Z
2017-JUL-1 9:58:23
2017-6-1 9:58:23

Notice I'm getting hour = 9 while expected 7

Questions

  1. Why this result
  2. How to get the right result ?

Thanks !

Upvotes: 0

Views: 107

Answers (1)

RubenDG
RubenDG

Reputation: 1405

Why this result

Due to this line: ZonedDateTime zdt = ZonedDateTime.ofInstant(instant, ZoneId.systemDefault());
You're forcing your time zone over the one defined in the dateStr, so the Calendar will use your time zone instead of the original one.

How to get the right result ?

Change your getFormatedDate method to:

private Calendar getFormatedDate(final String dateStr) {
    final ZonedDateTime zdt = ZonedDateTime.parse(dateStr);
    return GregorianCalendar.from(zdt);
}

Upvotes: 1

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