c# - How can i sort Arraylist with a class?

Question

How can i soth below arraylist according to int value. But if you compiled below codes error : Invalid Operation Exception... Detail : Failed to compare two elements in the array.

namespace SortArray
{
    class Program
    {
        static void Main(string[] args)
        {
            ArrayList otomobil = new ArrayList();
            otomobil.Add(new Otomobil() { Model = 2000, Marka = "mercedes", Renk = "K?rm?z?" });
            otomobil.Add(new Otomobil() { Model = 2002, Marka = "Opel", Renk = "Ye?il" });
            otomobil.Add(new Otomobil() { Model = 2009, Marka = "Audi", Renk = "Mavi" });

            otomobil.Sort();
            for (int i = 0; i < otomobil.Count; i++)
            {
                Console.WriteLine(otomobil[i].ToString());
            }

        }
    }

    public class Otomobil
    {
        public string Marka { get; set; }
        public int Model { get; set; }
        public string Renk { get; set; }

        public Otomobil()
        {

        }

        public override string ToString()
        {
            return Marka + "(" + Model.ToString() + "-" + Renk + ")";
        }

        public int CompareTo(object obj)
        {
            if (obj == null)
                return 1;



            Otomobil outer = obj as Otomobil;
            if (outer == null)
                throw new ArgumentException();

            if (this.Model > outer.Model)
                return 1;
            else if (this.Model < outer.Model)
                return -1;
            else return 0;
        } 
    }
}

Answer 1

class Otomobil : IComparable