calculate hours/minutes between two times in dart - flutter

Question

I want to get/calculate hours and minutes between two times in dart.
Example: if start_time is 17:30 and end_time is 09:00 (day after) it should return total: 15 hours 30 minutes
My code:
check_two_times_is_before(String start_time, String end_time){
var format = DateFormat("HH:mm");
var start = format.parse(start_time);
var end = format.parse(end_time);
if(start.isAfter(end)) {
// do something here
}
}

Answer 1

You can use difference method on DateTime class.
check_two_times_is_before(String start_time, String end_time){
var format = DateFormat("HH:mm");
var start = format.parse(start_time);
var end = format.parse(end_time);
if(start.isAfter(end)) {
end = end.add(Duration(days: 1));
Duration diff = end.difference(start);
final hours = diff.inHours;
final minutes = diff.inMinutes % 60;
print('$hours hours $minutes minutes');
}
}

Answer 2

You can try it with Duration class
Duration duration = end.difference(start).abs();
final hours = duration.inHours;
final minutes = duration.inMinutes % 60;
print('$hours hours $minutes minutes');

Answer 3

The question is pretty old but here is another solution which might help someone.
Duration duration = DateTime.fromMillisecondsSinceEpoch(timestmap).difference(DateTime.now()).abs();
final days = duration.inDays;
final hours = duration.inHours - (days * 24);
final minutes = duration.inMinutes - (days * 24 * 60) - (hours * 60);
final seconds = duration.inSeconds - (days * 24 * 60 * 60) - (hours * 60 * 60) - (minutes * 60);
Nothing to explain here really. We're just using basic algebra. We're getting the total number of milliseconds between the two timestamps and working that down to days, hours, minutes and seconds.