using System;

public class Program

{

    public static void Main()

    {

        var h1 = new Handler1();

        var h2 = new Handler2();

        var h3 = new Handler3();

        h1.SetSuccessor(h2);

        h2.SetSuccessor(h3);

        for(var i = 0; i < 30; i++){

            h1.CheckItem(i);

        }

    }

}

​

​

public interface IHandler{

​

    IHandler Handler { get;set; }

    void SetSuccessor(IHandler handler);

    void CheckItem(int itemToCheck);

​

}

​

​

public class Handler1 : IHandler{

​

    public IHandler Handler { get;set; }

    public void SetSuccessor(IHandler handler){

        Handler = handler;

    }

    public void CheckItem(int itemToCheck){

        if (itemToCheck < 10)

            Console.WriteLine("Handler 1: " + itemToCheck);

        else if (Handler != null)

            Handler.CheckItem(itemToCheck);

    } 

​

}

​

public class Handler2 : IHandler{

​

    public IHandler Handler { get;set; }

    public void SetSuccessor(IHandler handler){

        Handler = handler;

    }

    public void CheckItem(int itemToCheck){

        if (itemToCheck < 20)

            Console.WriteLine("Handler 2: " + itemToCheck);

        else if (Handler != null)

            Handler.CheckItem(itemToCheck);

    } 

​

}

​

public class Handler3 : IHandler{

​

    public IHandler Handler { get;set; }

    public void SetSuccessor(IHandler handler){

        Handler = handler;

    }

    public void CheckItem(int itemToCheck){

        if (itemToCheck < 30)

            Console.WriteLine("Handler 3: " + itemToCheck);

        else if (Handler != null)

            Handler.CheckItem(itemToCheck);

    } 

​

}