How do I create a DateTime instance in a specific timezone?

I wrote a package for this. It's called Instant, and it can fetch the latest DateTime in any given zone worldwide. Take a detailed look at https://aditya-kishore.gitbook.io/instant/

The basic usage to get a DateTime in a timezone is fairly simple.

Note: I assume below that your legacy service delivers a String with format HH:MM in 24 hr time, and that it doesn't deliver a date. If any of the following is untrue, lemme know and I'll change the code sample.

List<int> _hourmin (String parse) {
  List<int> timeinint = [];
  if (parse.length == 5) {
    //if parse is something like 10:00
    timeinint.add(int.parse(parse.substring(0,2))); //Add hours (10)
    timeinint.add(int.parse(parse.substring(3,5))); //Add minutes (0)
  } //hours >= 10
  if (parse.length == 4) {
    //if parse is something like 4:06
    timeinint.add(int.parse(parse.substring(0,1))); //Add hours (4)
    timeinint.add(int.parse(parse.substring(2,4))); //Add minutes (6)
  } //hours < 10
  return timeinint;
}

DateTime utcDateTimeFromZone(
    {@required String zone,
    int year = 0,
    int month = 0,
    int day = 0,
    int hour = 0,
    int minute = 0,
    int second = 0,
    int millisecond = 0,
    int microsecond = 0}) {

  hour = (hour - timeZoneOffsets[zone].truncate()) % 24; //Convert to UTC from timezone
  if (hour<0) {
    hour = 24 + hour;
  }
  minute = (minute - ((timeZoneOffsets[zone]%1)*60).round()) % 60;
  if (minute<0) {
    minute = 60 + minute;
  }
//Convert to UTC from timezone
  DateTime inUTC = DateTime.utc(year, month, day, hour, minute, second, millisecond, microsecond); //Initialize in UTC time
  return inUTC;
}

  //We get an array containing the hours minutes
  List<int> time = _hourmin("4:25"); //put your API call as the param here
  //This is what you need
  DateTime finished = utcDateTimeFromZone(zone: "EST", hour: time[0], minute: time[1]);

  print(formatTime(time: finished.toLocal())); //1:25 for me, because I'm PST, but this works with any local timezone

Hope that clears it up!

The included DateTime class only supports the local timezone or UTC but no specific timezone.

https://pub.dartlang.org/packages/timezone would provide that but it looks like it needs an update for Dart 2.0.0

https://pub.dartlang.org/packages/time_machine is a newer one.