Flutter: why can't I create a DateTime object with all 0 values?-CodePudding

So I want to make a Stopwatch in Flutter.

static void startTrip() {
  SharedPrefsHelper().setIsCurrentlyOnTrip(true);

  _elapsedTime = DateTime(
    0, //year
    0, //month
    0, //day
    0, //hour
    0, //minute
    0, //second
    0, //millisecond
    0, //microsecond
  );
  
  _timer = Timer.periodic(Duration(seconds: 1), (Timer timer) {
    _elapsedTime.add(Duration(seconds: 1));
    print('new time: $_elapsedTime');
    _controller.sink.add(_elapsedTime); //same object/reference, but this is for the StreamBuilder to update
  });

  //TODO
}

As you can see I first attempted to use a DateTime object to keep track of the time.
But DateTime(0, 0, 0, 0, 0, 0, 0, 0) initializes to -0001-11-30 00:00:00.000. And the value doesn't update after I try to add 1 second, it always prints out the same.

Go and try it out your self on dartpad by running this code:

DateTime elapsedTime = DateTime(0, 0, 0, 0, 0, 0, 0, 0);
print(elapsedTime);
elapsedTime.add(Duration(seconds: 1));
print(elapsedTime);

Does anyone know why this happens?
For now I will just use an int to keep track of the time instead and do the formatting myself.

P.S so this is how I did it, if anyone wants the code:

int hours = elapsedTime ~/ 3600;
int minutes = (elapsedTime % 3600) ~/ 60; //get rid of all additional hours, then divide by 60
int seconds = elapsedTime % 60; //get rid of all additional minutes

String h = hours > 9 ? hours.toString() : '0$hours';
String m = minutes > 9 ? minutes.toString() : '0$minutes';
String s = seconds > 9 ? seconds.toString() : '0$seconds';

CodePudding user response：

You can try this:

DateTime elapsedTime = DateTime.utc(0);
print(elapsedTime);
elapsedTime = elapsedTime.add(Duration(seconds: 1));
print(elapsedTime);

Note: The lowest value for day and month is 1 and not 0.