How to sort TimeOfDay list from earliest to latest time? - flutter

Question

I need to display a schedule for users that displays times from earliest to latest time. I have a TimeOfDay list containing times and need it to be sorted from earliest to latest time. I made a function for it, but keep getting _TypeError (type 'TimeOfDay' is not a subtype of type 'String') when I run my code. Since I utilize the function inside a Column in my Widget build code block, I think it has to return a widget. Please let me know how I can resolve this error and efficiently sort my list through a function. The code for my function is below, any help would be appreciated!
listOrder(l) {
l.sort((a,b) => DateTime.parse(a).compareTo(DateTime.parse(b)));
return Text('Done!');
}

Answer 1

DateTime.parse expects a String input, not a TimeOfDay instance.
If you want to sort a List<TimeOfDay>, you need to provide a comparison function that compares TimeOfDay instances:
int compareTimeOfDay(TimeOfDay time1, TimeOfDay time2) {
var totalMinutes1 = time1.hour * 60 + time1.minute;
var totalMinutes2 = time2.hour * 60 + time2.minute;
return totalMinutes1.compareTo(totalMinutes2);
}
void main() {
var list = [
TimeOfDay(hour: 12, minute: 59),
TimeOfDay(hour: 2, minute: 3),
TimeOfDay(hour: 22, minute: 10),
TimeOfDay(hour: 9, minute: 30),
];
list.sort(compareTimeOfDay);
print(list);
}

Answer 2

i think you are missing return value form sort method. since you are using curly brackets,
here i try on dartpad is working fine
void main() {
List date = ['2022-02-02','2022-02-15','2022-02-01'];
date.sort((a,b) => DateTime.parse(a).compareTo(DateTime.parse(b)));
print(date); //result : [2022-02-01, 2022-02-02, 2022-02-15]
}
if you have 1 argument, you can simplify with arrow => , but if you have more than 1, use brackets {}
l.sort((a,b){
return DateTime.parse(a).compareTo(DateTime.parse(b)); // see i add a return syntax
});