C# - Handling an Event Declared in an Interface

// C# program for Illustrating Handling an 
// Event Declared in an Interface through C#

using System;
using System.Collections.Generic;

namespace GFG {
    // <summary>
    // Video class
    // </summary>
    public class Video {
        public string Name;
    }

    // Interface IChannel has an event VideoAdded
    public interface IChannel {
        event EventHandler VideoAdded;
    }

    // Channel class - A Publisher of the event
    public class Channel : IChannel 
    {
        public event EventHandler VideoAdded;
        public string Name
        {
            get;
            set;
        }

        public List<Video> ListOfVideos = new List<Video>();
        public void AddVideo()
        {
            Video video = new Video();
            video.Name = "EventHandler in c#";
            ListOfVideos.Add(video);

            // Notify all the subscribers
            NotifyAllSubscribers();
        }

        public void NotifyAllSubscribers()
        {
            EventHandler handler = VideoAdded;

            // safety check to avoid null reference error
            if (handler != null) {
                // Invoking the event VideoAdded.
                // 1st parameter - sender object i.e Channel
                // class in this case 2nd parameter - object of
                // type EventArgs()
                handler(this, new EventArgs());
            }
        }
    }

    // receiver 1
    public class Subscriber_A {
        public string Name
        {
            get;
            set;
        }

        public Subscriber_A(Channel ch)
        {
            // Subscribing to the publisher's event
            ch.VideoAdded
                += new EventHandler(ReceiveVideoNotification);
        }

        // Method that is to be executed when the event is
        // triggered.
        public void ReceiveVideoNotification(object sender,
                                             EventArgs e)
        {
            Console.WriteLine(
                "Hello {0}, a new video has 
                 been uploaded by GeeksForGeeks",
                Name);
            Console.WriteLine();
        }
    }

    // receiver 2
    public class Subscriber_B {
        public string Name
        {
            get;
            set;
        }

        public Subscriber_B(Channel channel)
        {
            // Subscribing to the publisher's event
            channel.VideoAdded
                += new EventHandler(ReceiveVideoNotification);
        }

        // Method that is to be executed when the event is
        // triggered.
        public void ReceiveVideoNotification(object sender,
                                             EventArgs e)
        {
            Console.WriteLine(
                "Hello {0}, a new video has been 
                 uploaded by GeeksForGeeks",
                Name);
            Console.WriteLine();
        }
    }

    class Program {
        static void Main(string[] args)
        {
            Channel channel = new Channel();

            channel.Name = "GeeksForGeeks";

            Subscriber_A A = new Subscriber_A(channel);
            A.Name = "Geek_1";
          
            Subscriber_B B = new Subscriber_B(channel);
              B.Name = "Geek_2";

            // Adding a video
            channel.AddVideo();
        }
    }
}