How can I get the difference between 2 times? - flutter

Question

I'm working on a flutter app as a project and I'm stuck with how to get the difference between two times. The first one I'm getting is from firebase as a String, which I then format to a DateTime using this:DateTime.parse(snapshot.documents[i].data['from']) and it gives me 14:00 for example. Then, the second is DateTime.now().
I tried all methods difference, subtract, but nothing works!
Please help me to get the exact duration between those 2 times.
I need this for a Count Down Timer.
This is an overview of my code:
.......
class _ActualPositionState extends State<ActualPosition>
with TickerProviderStateMixin {
AnimationController controller;
bool hide = true;
var doc;
String get timerString {
Duration duration = controller.duration * controller.value;
return '${duration.inHours}:${duration.inMinutes % 60}:${(duration.inSeconds % 60).toString().padLeft(2, '0')}';
}
#override
void initState() {
super.initState();
var d = Firestore.instance
.collection('users')
.document(widget.uid);
d.get().then((d) {
if (d.data['parking']) {
setState(() {
hide = false;
});
Firestore.instance
.collection('historyParks')
.where('idUser', isEqualTo: widget.uid)
.getDocuments()
.then((QuerySnapshot snapshot) {
if (snapshot.documents.length == 1) {
for (var i = 0; i < snapshot.documents.length; i++) {
if (snapshot.documents[i].data['date'] ==
DateFormat('EEE d MMM').format(DateTime.now())) {
setState(() {
doc = snapshot.documents[i].data;
});
Duration t = DateTime.parse(snapshot.documents[i].data['until'])
.difference(DateTime.parse(
DateFormat("H:m:s").format(DateTime.now())));
print(t);
}
}
}
});
}
});
controller = AnimationController(
duration: Duration(hours: 1, seconds: 10),
vsync: this,
);
controller.reverse(from: controller.value == 0.0 ? 1.0 : controller.value);
}
double screenHeight;
#override
Widget build(BuildContext context) {
screenHeight = MediaQuery.of(context).size.height;
return Scaffold(
.............

Answer 1

you can find the difference between to times by using:
DateTime.now().difference(your_start_time_here);
something like this:
var startTime = DateTime(2020, 02, 20, 10, 30); // TODO: change this to your DateTime from firebase
var currentTime = DateTime.now();
var diff = currentTime.difference(startTime).inDays; // HINT: you can use .inDays, inHours, .inMinutes or .inSeconds according to your need.
example from DartPad:
void main() {
final startTime = DateTime(2020, 02, 20, 10, 30);
final currentTime = DateTime.now();
final diff_dy = currentTime.difference(startTime).inDays;
final diff_hr = currentTime.difference(startTime).inHours;
final diff_mn = currentTime.difference(startTime).inMinutes;
final diff_sc = currentTime.difference(startTime).inSeconds;
print(diff_dy);
print(diff_hr);
print(diff_mn);
print(diff_sc);
}
Output: 3,
77,
4639,
278381,
Hope this helped!!

Answer 2

You can use the DateTime class to find out the difference between two dates.
DateTime dateTimeCreatedAt = DateTime.parse('2019-9-11');
DateTime dateTimeNow = DateTime.now();
final differenceInDays = dateTimeNow.difference(dateTimeCreatedAt).inDays;
print('$differenceInDays');
final differenceInMonths = dateTimeNow.difference(dateTimeCreatedAt).inMonths;
print('$differenceInMonths');

Answer 3

Use this code:
var time1 = "14:00";
var time2 = "09:00";
Future<int> getDifference(String time1, String time2) async
{
DateFormat dateFormat = DateFormat("yyyy-MM-dd");
var _date = dateFormat.format(DateTime.now());
DateTime a = DateTime.parse('$_date $time1:00');
DateTime b = DateTime.parse('$_date $time2:00');
print('a $a');
print('b $a');
print("${b.difference(a).inHours}");
print("${b.difference(a).inMinutes}");
print("${b.difference(a).inSeconds}");
return b.difference(a).inHours;
}

Answer 4

To compute a difference between two times, you need two DateTime objects. If you have times without dates, you will need to pick a date. Note that this is important because the difference between two times can depend on the date if you're using a local timezone that observes Daylight Saving Time.
If your goal is to show how long it will be from now to the next specified time in the local timezone:
import 'package:intl/intl.dart';
/// Returns the [Duration] from the current time to the next occurrence of the
/// specified time.
///
/// Always returns a non-negative [Duration].
Duration timeToNext(int hour, int minute, int second) {
var now = DateTime.now();
var nextTime = DateTime(now.year, now.month, now.day, hour, minute, second);
// If the time precedes the current time, treat it as a time for tomorrow.
if (nextTime.isBefore(now)) {
// Note that this is not the same as `nextTime.add(Duration(days: 1))` across
// DST changes.
nextTime = DateTime(now.year, now.month, now.day + 1, hour, minute, second);
}
return nextTime.difference(now);
}
void main() {
var timeString = '14:00';
// Format for a 24-hour time. See the [DateFormat] documentation for other
// format specifiers.
var timeFormat = DateFormat('HH:mm');
// Parsing the time as a UTC time is important in case the specified time
// isn't valid for the local timezone on [DateFormat]'s default date.
var time = timeFormat.parse(timeString, true);
print(timeToNext(time.hour, time.minute, time.second));
}

Answer 5

You can use this approch
getTime(time) {
if (!DateTime.now().difference(time).isNegative) {
if (DateTime.now().difference(time).inMinutes < 1) {
return "a few seconds ago";
} else if (DateTime.now().difference(time).inMinutes < 60) {
return "${DateTime.now().difference(time).inMinutes} minutes ago";
} else if (DateTime.now().difference(time).inMinutes < 1440) {
return "${DateTime.now().difference(time).inHours} hours ago";
} else if (DateTime.now().difference(time).inMinutes > 1440) {
return "${DateTime.now().difference(time).inDays} days ago";
}
}
}
And You can call it getTime(time) Where time is DateTime Object.