在 API 级别 21 上将日期的时区更改为 UTC

Question

I have a Date and I need to change timezone of this date to UTC. The code below does not work.

    Calendar cal = Calendar.getInstance();

    cal.setTimeZone(TimeZone.getTimeZone("UTC"));
    cal.setTimeInMillis(dateLocal.getTime());

    return new Date(cal.getTimeInMillis());

On the Stackoverflow all examples return either a String or use API 26. How can I solve my problem on the Android API 21?

Answer 1

Try this:

public Date getDateInUtc() {
        String DATE_FORMAT = "yyyy-MM-dd HH:mm:ss";
        Date dateToReturn = null;

        SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT, Locale.getDefault());
        sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
        SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_FORMAT, Locale.getDefault());
        String utcTime = sdf.format(new Date());

        try {
            dateToReturn = dateFormat.parse(utcTime);
        } catch (ParseException e) {
            e.printStackTrace();
        }

        return dateToReturn;
    }

Answer 2

Use cal.getTime(); which returns date

Answer 3

The same result you can get without SimpleDateFormat:

public Date dateInUtc(Date input) {
    Calendar inputCalendar = Calendar.getInstance();
    inputCalendar.setTime(input);
    TimeZone timeZone = inputCalendar.getTimeZone();
    long timeInUtc = input.getTime() - timeZone.getRawOffset();

    Calendar outputCalendar = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
    outputCalendar.setTimeInMillis(timeInUtc);
    return outputCalendar.getTime();
}