报社更新报纸内容，读者获取更新

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace DesignPytternDemo
{


    /// <summary>
    /// 利用事件实现观察者
    /// </summary>
    /// <param name="sender"></param>

    public delegate void UpdatePaper(object sender);


    /// <summary>
    /// 报社
    /// </summary>
    public class Paper
    {
        public event UpdatePaper OnChange;


        /// <summary>
        /// 更新报纸了
        /// </summary>
        public void ChangeData()
        {
            if (null != OnChange)
            {
                OnChange.Invoke("new data");
            }
        }
    }


    /// <summary>
    /// 读者
    /// </summary>
    public class Reader
    {


        public void ReadNews(object news)
        {
            Console.Write(news.ToString());
        }
    }




}

Paper p = new Paper();
            Reader reader1 = new Reader();
            Reader reader2 = new Reader();


            p.OnChange += reader1.ReadNews;
            p.OnChange += reader2.ReadNews;


            p.ChangeData();
            Console.ReadLine();