ネタ。多分こんな使い方しないと思うけど、拡張メソッドで Add を追加してあげたらそれっぽくなるかも?
using System; using System.Collections.Generic; public static class SortedListExtensions { public static void Add<T>(this SortedList<int, T> target, T source) { target.Add(target.Count, source); } } class Program { static void Main(string[] args) { var sortedList = new SortedList<int, Item>(); sortedList.Add(new Item() { Id = 2, Name = "かきく" }); sortedList.Add(new Item() { Id = 1, Name = "あいう" }); Console.WriteLine(sortedList[0]); Console.WriteLine(sortedList[1]); var list = new List<Item>() { new Item() { Id = 2, Name = "かきく" }, new Item() { Id = 1, Name = "あいう" } }; Console.WriteLine(list[0]); Console.WriteLine(list[1]); Console.ReadKey(); } } class Item { public int Id { get; set; } public string Name { get; set; } public override string ToString() { return string.Format("Id:{0} Name:{1}", Id, Name); } }