C# Event – Understanding C# events – Part 3

Before going further it is really important to go through the Part 1 and Part 2.

Part 1 – Click Here.

Part 2 – Click Here.

AS discussed in Part 2, I will create an application based on Events. So create BallEventArgs  class as shown below –

public class BallEventArgs : EventArgs

    {

        public int Height { get; set; }

        public int Length { get; set; } 

        public BallEventArgs(int h, int l)

        {

            Height = h;

            Length = l;

        }

    }

Create Ball class as hown below with event declaration –
public class Ball
    {
        //declare event BallInGround
        public event EventHandler BallInGround; 

        /// <summary>

        /// method used for raising the event BallInGround

        /// </summary>

        /// <param name="e">BallEventArgs object</param>

        public void OnBallInGround(BallEventArgs e)

        {

            if (BallInGround != null)

            {

                BallInGround(this, e);

            }

        }

    }

Add a Fielder class as shown below –

public class Fielder

    {       

        public Fielder(Ball ball)

        {

            //register event

            ball.BallInGround += new EventHandler(ball_BallInGround);

        }

        //event handler method

        void ball_BallInGround(object sender, EventArgs e)

        {

            if (e is BallEventArgs)

            {

                BallEventArgs ballEventArgs = e as BallEventArgs;

                if (ballEventArgs.Height < 60)

                {

                    Console.WriteLine("Fielder: caught the ball!!");

                }

                else if (ballEventArgs.Height > 90 && ballEventArgs.Length > 90)

                {

                    Console.WriteLine("Fielder: It's a Six!!");

                }

                else

                {

                    Console.WriteLine("Fielder: field the ball!!");

                }

            }

        }

    }
 

Fan class is as follows –
public class Fan
    {
        public Fan(Ball ball)
        {
            ball.BallInGround += new EventHandler(ball_BallInGround);
        }

        void ball_BallInGround(object sender, EventArgs e)

        {

            if (e is BallEventArgs)

            {

                BallEventArgs ballEventArgs = e as BallEventArgs;

                if (ballEventArgs.Height < 60)

                {

                    Console.WriteLine("Fan: ohh nooo..it's a wicket down!!");

                }

                else if (ballEventArgs.Height > 90 && ballEventArgs.Length > 90)

                {

                    Console.WriteLine("Fan: yoo hoooo it's a six!!");

                }

                else

                {

                    Console.WriteLine("Fan: boring...!!");

                }

                Console.ReadLine();

            }

        }

    }

Form code behind class wil be as follows –

public partial class Form1 : Form

    {

        private Ball ball = null;

        Fan fan = null;

        Fielder fielder = null;

        public Form1()

        {

            InitializeComponent();           

            ball = new Ball();

            fielder = new Fielder(ball);

            fan = new Fan(ball);           

        }

        private void btnHit_Click(object sender, EventArgs e)

        {

            BallEventArgs ballEventArgs = new BallEventArgs(Convert.ToInt16(txtHeight.Text), Convert.ToInt16(txtLength.Text));

            ball.OnBallInGround(ballEventArgs);

        }

    }

Following are the replies received on different inputs in Output window –

 

 

 

This is how you can use Events in c#. Hope this application has given you basic implementation details related to C# Event. Now let’s discuss few real life implementations of C# events and concepts related to C# Events in Part 4(In Progress).