compareDateTimeNullable method

int compareDateTimeNullable(DateTime? other)

Compares two nullable DateTimes for sorting purposes.

Null DateTimes are considered to be before non-null DateTimes.

Returns:

• 0 if both DateTimes are considered equal (both null or representing the same point in time).
• -1 if this nullable DateTime is considered smaller (comes before) the other nullable DateTime.
• 1 if this nullable DateTime is considered larger (comes after) the other nullable DateTime.

Example Usage:

DateTime? dt1 = DateTime.now();
DateTime? dt2 = dt1.add(Duration(days: 1));
DateTime? dt3 = null;

dt1.compareDateTimeNullable(dt2); // -1
dt2.compareDateTimeNullable(dt1); // 1
dt1.compareDateTimeNullable(dt1); // 0
dt3.compareDateTimeNullable(dt1); // -1 (null is considered before non-null)
dt1.compareDateTimeNullable(dt3); // 1 (non-null is considered after null)
dt3.compareDateTimeNullable(null); // 0 (both null are considered equal)

Implementation

int compareDateTimeNullable(DateTime? other) {
  if (this == other) {
    return 0;
  }

  if (this == null) {
    return -1;
  }

  if (other == null) {
    return 1;
  }

  return this!.compareTo(other);
}