public class Program
  {
    //定义一个为委托
    public delegate void Entrust(string str);
    static void Main(string[] args)
    {
      Entrust callback = new Entrust(CallBack); //把方法赋值给委托
      Thread th = new Thread(Fun);
      th.IsBackground = true;
      th.Start(callback);//将委托传递到子线程中
      Console.ReadKey();
    }
    private static void Fun(object obj) {
      //注意：线程的参数是object类型
      for (int i = 1; i <= 10; i++)
      {
        Console.WriteLine("子线程循环操作第 {0} 次",i);
        Thread.Sleep(500);
      }
      Entrust callback = obj as Entrust;//强转为委托
      callback("我是子线程，我执行完毕了，通知主线程");
      //子线程的循环执行完了就执行主线程的方法
    }
    //主线程的方法
    private static void CallBack(string str) {
      Console.WriteLine(str);
    }
  }

public class Program
  {
    //定义一个为委托
    public delegate void Entrust(string str);
    static void Main(string[] args)
    {
      Action<string> callback = ((string str) => { Console.WriteLine(str); });
      //Lamuda表达式
      Thread th = new Thread(Fun);
      th.IsBackground = true;
      th.Start(callback);
      Console.ReadKey();
    }
    private static void Fun(object obj) {
      for (int i = 1; i <= 10; i++)
      {
        Console.WriteLine("子线程循环操作第 {0} 次",i);
        Thread.Sleep(500);
      }
      Action<string> callback = obj as Action<string>;
      callback("我是子线程，我执行完毕了，通知主线程");
    }

  }
 //上面的Lamuda表达式也可以回城匿名函数
 //Action<string> callback = delegate(string str) { Console.WriteLine(str); };