Is there a sorted collection type in .NET?

Question

I\'m looking for a container that keeps all its items in order. I looked at SortedList, but that requires a separate key, and does not allow duplicate keys. I could also j

Answer 1

If you just want to stick with the standard collections then the Sort(IComparer<>) function of the List<> class is one that often gets ignored. All you need to do is create a suitable Comparer<> for your objects. For example:

public class PositionDateComparer : IComparer
{
    public int Compare(VehiclePosition x, VehiclePosition y)
    {
        if (x.DateTime == DateTime.MinValue)
        {
            if (y.DateTime == DateTime.MinValue)
            {
                // If x is null and y is null, they're
                // equal. 
                return 0;
            }

            // If x is null and y is not null, y
            // is greater. 
            return -1;
        }

        // If x is not null...
        //
        if (y.DateTime == DateTime.MinValue)
        // ...and y is null, x is greater.
        {
            return 1;
        }

        // ...and y is not null, compare the dates
        //
        if (x.DateTime == y.DateTime)
        {
            // x and y are equal
            return 0;
        }

        if (x.DateTime > y.DateTime)
        {
            // x is greater
            return 1;
        }

        // y is greater
        return -1;
    }
}

Then just perform a vehiclePositionsList.Sort(new PositionDateComparer()) whenever you want to sort the list before accessing it. I realise that this might not be as simple as a container which automatically sorts every time you add a new object, but for many (like me!) this might be enough to do the job successfully without requiring any additional libraries.