DateTime comparison in dart

Simply use the methods isAfter(), isBefore() or isAtSameMomentAs() from DateTime.

Other alternative, use compareTo(DateTime other), as in the docs:

Compares this DateTime object to [other],
returning zero if the values are equal.

Returns a negative value if this DateTime [isBefore] [other]. It returns 0
if it [isAtSameMomentAs] [other], and returns a positive value otherwise
(when this [isAfter] [other]).

Here a code example of sorting dates:

void main() {
  var list = [
    DateTime.now().add(Duration(days: 3)),
    DateTime.now().add(Duration(days: 2)),
    DateTime.now(),
    DateTime.now().subtract(Duration(days: 1))
  ];

  list.sort((a, b) => a.compareTo(b));
  print(list);
}

See it working here.