Description
This article contains a c# code which makes use of the concepts of Events and Interfaces together. The attached code makes use of the concepts of Events and Interfaces together. This is a simple Windows form which contains a textbox, labels and a button. The textbox receives the focus on page load. The keydown events of the textbox are captured and whenever any of the arrow keys is pressed, an Event is fired through an Interface which displays the name of the arrow key pressed.
How to Use
Copy the below given code in a text editor and save it as a .cs file. Compile it using "csc <filename>" and Run the .exe file.
Source Code
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
namespace Events_Interfaces
{
public delegate void dele();
public interface IEvents
{
event dele event1;
void FireEvent();
}
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.Label label1;
private System.Windows.Forms.TextBox textBox1;
private System.Windows.Forms.Label label2;
private System.Windows.Forms.Button button1;
private System.Windows.Forms.Label label3;
private System.ComponentModel.Container components = null;
public Form1()
{
InitializeComponent();
}
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}
#region Windows Form Designer generated code
private void InitializeComponent()
{
this.textBox1 = new System.Windows.Forms.TextBox();
this.label1 = new System.Windows.Forms.Label();
this.button1 = new System.Windows.Forms.Button();
this.label2 = new System.Windows.Forms.Label();
this.label3 = new System.Windows.Forms.Label();
this.SuspendLayout();
this.textBox1.Location = new System.Drawing.Point(8, 80);
this.textBox1.Name = "textBox1";
this.textBox1.Size = new System.Drawing.Size(56,23);
this.textBox1.TabIndex = 1;
this.textBox1.Text = "";
this.textBox1.KeyDown += new System.Windows.Forms.KeyEventHandler(this.Key_Press);
this.label1.Location = new System.Drawing.Point(16, 16);
this.label1.Name = "label1";
this.label1.Size = new System.Drawing.Size(256, 64);
this.label1.TabIndex = 0;
this.label1.Text = "Whenever you use the arrow keys inside the text box, Corresponding events will be" + " fired to display the label appropriately. Have a try!!";
this.button1.Location = new System.Drawing.Point(240, 112);
this.button1.Name = "button1";
this.button1.Size = new System.Drawing.Size(48,23);
this.button1.TabIndex = 3;
this.button1.Text = "Exit";
this.button1.Click += new System.EventHandler(this.button1_Click);
//
// label2
//
this.label2.Location = new System.Drawing.Point(88, 80);
this.label2.Name = "label2";
this.label2.Size = new System.Drawing.Size(184,23);
this.label2.TabIndex = 2;
this.label2.TextAlign = System.Drawing.ContentAlignment.MiddleCenter;
//
// label3
//
this.label3.Location = new System.Drawing.Point(8, 104);
this.label3.Name = "label3";
this.label3.Size = new System.Drawing.Size(64,23);
this.label3.TabIndex = 4;
this.label3.TextAlign = System.Drawing.ContentAlignment.MiddleCenter;
//
// Form1
//
this.AutoScaleBaseSize = new System.Drawing.Size(6, 16);
this.ClientSize = new System.Drawing.Size(292,141);
this.Controls.AddRange(new System.Windows.Forms.Control[] {this.label3,this.button1,this.label2,this.textBox1,
this.label1});
this.Font = new System.Drawing.Font("Comic Sans MS", 8.25F, System.Drawing.FontStyle.Regular,
System.Drawing.GraphicsUnit.Point, ((System.Byte)(0)));
this.Name = "Form1";
this.Text = "Events";
this.ResumeLayout(false);
}
#endregion
static void Main()
{
Application.Run(new Form1());
}
private void Key_Press(object sender, System.Windows.Forms.KeyEventArgs e)
{
textBox1.Text = "";
label2.Text = "";
string keyId = e.KeyCode.ToString();
switch (keyId)
{
case "Right":
label3.Text = "";
IEvents id1 = new EventClass1();
id1.event1 += new dele(EventFired1);
id1.FireEvent();
break;
case "Left":
label3.Text = "";
IEvents id2 = new EventClass2();
id2.event1 += new dele(EventFired2);
id2.FireEvent();
break;
case "Down":
label3.Text = "";
IEvents id3 = new EventClass3();
id3.event1 += new dele(EventFired3);
id3.FireEvent();
break;
case "Up":
label3.Text = "";
IEvents id4 = new EventClass4();
id4.event1 += new dele(EventFired4);
id4.FireEvent();
break;
default:
label3.Text = keyId;
break;
}
}
public void EventFired1()
{
label2.Text = "";
label2.Text = "You pressed RIGHT arrow key";
}
public void EventFired2()
{
label2.Text = "";
label2.Text = "You pressed LEFT arrow key";
}
public void EventFired3()
{
label2.Text = "";
label2.Text = "You pressed DOWN arrow key";
}
public void EventFired4()
{
label2.Text = "";
label2.Text = "You pressed UP arrow key";
}
private void button1_Click(object sender, System.EventArgs e)
{
Application.Exit();
}
}
public class EventClass1 : IEvents
{
public event dele event1;
public void FireEvent()
{
event1();
}
}
public class EventClass2 : IEvents
{
public event dele event1;
public void FireEvent()
{
event1();
}
}
public class EventClass3 : IEvents
{
public event dele event1;
public void FireEvent()
{
event1();
}
}
public class EventClass4 : IEvents
{
public event dele event1;
public void FireEvent()
{
event1();
}
}
}
//--------------------------------------------------
//References that may be needed while compiling
//System
//System.Drawing
//System.Windows.Forms