Convert Local time to UTC and vice versa

Question

I'm working on Android application, and I want to convert local time (device time) into UTC and save it in database. After retrieving it from database I have to convert it again and display in the device's time zone. Can anyone suggest how to do this in Java?

Answer 1

I converted local time to GMT/UTC and vice versa using these two methods and this works fine without any problem for me.

public static Date localToGMT() {
    Date date = new Date();
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
    sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
    Date gmt = new Date(sdf.format(date));
    return gmt;
}

pass the GMT/UTC date which you want to convert into device local time to this method:

public static Date gmttoLocalDate(Date date) {

    String timeZone = Calendar.getInstance().getTimeZone().getID();
    Date local = new Date(date.getTime() + TimeZone.getTimeZone(timeZone).getOffset(date.getTime()));
    return local
}