using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Collections.ObjectModel;namespace Collection_Generic2{    class Program    {        static void Main(string[] args)        {            //初始化类            dinosaurs dino = new dinosaurs();            dino.Changed += ChangeHandler;//这个地方理解的不是很好            dino.Add("Psiticosaurus");            dino.Add("Caudipteryx");            dino.Add("Compsognathus");            dino.Add("Muttaburrasaurus");            Display(dino);            Console.WriteLine("\n IndexOf(\"Muttaburrasaurus\"):{0}", dino.IndexOf("Muttaburrasaurus"));                        Console.WriteLine("\n Contains(\"Caudipteryx\"):{0}",                dino.Contains("Caudipteryx"));                            Console.WriteLine("\n Insert(2,\"Nanotyrannus\")");                dino.Insert(2,"Nanotyrannus");             Console.WriteLine("\n dino[2]:{0}",dino[2]);            Console.WriteLine("\n dino[2]=\"Microraptor\"",                dino[2]="Microraptor");            Console.WriteLine("\n Remove (\"Microraptor\")");            dino.Remove("Microraptor");            Console.WriteLine("\n RemoveAt(0)");            dino.RemoveAt(0);            Display(dino);                            Console.ReadLine();        }        private static void ChangeHandler(object source, dinosaursChangedEventArgs e)        {            if (e.ChangeType == ChangeType.Replaced)            {                Console.WriteLine("{0} was replaced with {1}", e.ChangedItem, e.ReplaceWith);            }            else if (e.ChangeType == ChangeType.Cleared)            {                Console.WriteLine("The dinosaur list was cleared");            }            else            {                Console.WriteLine("{0} was {1}", e.ChangedItem, e.ChangeType);            }        }        private static void Display(Collection<string> cs)        {            Console.WriteLine();            foreach (string item in cs)            {                Console.WriteLine(item);            }        }    }}

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Collections.ObjectModel;namespace Collection_Generic2{    //继承泛型集合    class dinosaurs : Collection<string>    {        //该处类似于侦查其是否发送改变，一旦发生改变，则触发方法        public event EventHandler<dinosaursChangedEventArgs> Changed;        /// <summary>        /// 重写InsertItem方法        /// </summary>        /// <param name="index"></param>        /// <param name="item"></param>        protected override void InsertItem(int index, string newItem)        {            base.InsertItem(index, newItem);            EventHandler<dinosaursChangedEventArgs> temp = Changed;            if (temp != null)//增强稳健型            {                //如果发生改变，那么就添加一个新的项目进入指定位置                //this在这里是什么作用呢?没有想得特别明白                temp(this, new dinosaursChangedEventArgs(ChangeType.Added, newItem, null));            }        }        /// <summary>        /// 这个更换的功能的重写        /// </summary>        /// <param name="index"></param>        /// <param name="NewItem"></param>        protected override void SetItem(int index, string NewItem)        {            string replaced = Items[index];            base.SetItem(index, NewItem);            EventHandler<dinosaursChangedEventArgs> temp = Changed;            if (temp != null)            {                temp(this, new dinosaursChangedEventArgs(ChangeType.Replaced, replaced, NewItem));            }        }        /// <summary>        /// 重写移除操作        /// </summary>        /// <param name="index"></param>        protected override void RemoveItem(int index)        {            //Items获取其列表的内容            string removedItem = Items[index];            base.RemoveItem(index);            //代理改变这一事件,将其进行赋值            EventHandler<dinosaursChangedEventArgs> temp = Changed;            if (temp != null)            {                temp(this, new dinosaursChangedEventArgs(ChangeType.Removed, removedItem, null));            }        }        protected override void ClearItems()        {            base.ClearItems();            EventHandler<dinosaursChangedEventArgs> temp = Changed;            if (temp!=null)            {                temp(this,new dinosaursChangedEventArgs(ChangeType.Cleared,null,null));            }        }    }    /// <summary>    /// 改变的事件的参数    /// </summary>    public class dinosaursChangedEventArgs : EventArgs    {        public readonly string ChangedItem;        public readonly ChangeType ChangeType;        public readonly string ReplaceWith;        /// <summary>        /// 和类名相同，这样它应该算作重载        /// 其内容是通过重载，对类的三个属性进行赋值        /// </summary>        /// <param name="change"></param>        /// <param name="item"></param>        /// <param name="replacement"></param>        public dinosaursChangedEventArgs(ChangeType change, string item, string replacement)        {            ChangeType = change;            ChangedItem = item;            ReplaceWith = replacement;        }    }    /// <summary>    /// 将类型的四种操作实现枚举，枚举定义后面需要增加分号    /// 因为是一个定义，而非方法或类    /// </summary>    public enum ChangeType    {        Added,        Removed,        Replaced,        Cleared    };}