Let's Play Around With Composite Design Pattern

Introduction

Today, in this article let's play around with one of the interesting and most useful concepts of design patterns, which will be hosted in a web app.

Question: What is Composite Pattern?

In simple terms "Each independent object is led to lead an independent life, which creates a customized tree structure with many reference objects".

I think we are now good to go and implement this wonderful concept.

Step 1: The complete code of Default.aspx looks like this:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="CompositeDesignPatternApp.Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

</head>

<body>

<div>

Composite Pattern - Design Patterns</h1>

<table>

<tr>

<td>

<asp:Label ID="Label1" runat="server" Text="Please Enter First Number" Font-Size="Small"

Font-Bold="true" Font-Italic="true" Font-Names="Verdana"></asp:Label>

</td>

<td>

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

</td>

</tr>

<tr>

<td>

<asp:Label ID="Label2" runat="server" Text="Please Enter Second Number" Font-Size="Small"

Font-Bold="true" Font-Italic="true" Font-Names="Verdana"></asp:Label>

</td>

<td>

<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>

</td>

</tr>

<tr>

<asp:Button ID="Button1" runat="server" Text="Addition" Width="165px" Font-Names="Verdana"

BackColor="Orange" OnClick="Button1Click" />

</td>

</tr>

<tr>

<asp:Button ID="Button2" runat="server" Text="Subtraction" Width="165px" Font-Names="Verdana"

BackColor="Orange" OnClick="Button2Click" />

</td>

</tr>

<tr>

<asp:Button ID="Button3" runat="server" Text="Multiplication" Width="165px" Font-Names="Verdana"

BackColor="Orange" OnClick="Button3Click" />

</td>

</tr>

<tr>

<asp:Button ID="Button4" runat="server" Text="Division" Width="165px" Font-Names="Verdana"

BackColor="Orange" OnClick="Button4Click" />

</td>

</tr>

</table>

<table>

<tr>

<asp:Label ID="lblResult" runat="server" Font-Names="Verdana"></asp:Label>

</td>

</tr>

</table>

</center>

</div>

</form>

</body>

</html>

Step 2: The complete code of IArthmetic.cs looks like this:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace CompositeDesignPatternApp
{
public interface IArthmetic { double Arthmetic(double a, double b);}
}

Step 3: The complete code of Addition.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

namespace CompositeDesignPatternApp

{

public class Addition : IArthmetic { public double Arthmetic(double a, double b) { return a + b; } }

}

Step 4: The complete code of Subtraction.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

namespace CompositeDesignPatternApp

{

public class Substraction : IArthmetic { public double Arthmetic(double a, double b) { return a - b; } }

}

Step 5: The complete code of Multiplication.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

namespace CompositeDesignPatternApp

{

public class Multiplication : IArthmetic { public double Arthmetic(double a, double b) { return a * b; } }

}

Step 6: The complete code of Division.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

namespace CompositeDesignPatternApp

{

public class Division : IArthmetic { public double Arthmetic(double a, double b) { return a / b; } }

}

Step 7: The complete code of Default.aspx.cs looks like this:

using System;

using System.Globalization;

namespace CompositeDesignPatternApp

{

public partial class Default : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

TextBox1.Focus();

}

protected void Button1Click(object sender, EventArgs e)

{

if(string.IsNullOrEmpty(TextBox1.Text)||string.IsNullOrEmpty(TextBox2.Text))

{

lblResult.Text = "Please Enter Some Values";

lblResult.ForeColor = System.Drawing.Color.Red;

}

else

{

lblResult.Text = "Addition Result of <b>" + TextBox1.Text + "</b> and <b>" + TextBox2.Text + "</b> is <b>" +_objAddition.Arthmetic(Convert.ToDouble(TextBox1.Text), Convert.ToDouble(TextBox2.Text)).ToString(CultureInfo.InvariantCulture)+"</b>";

TextBox1.Text = "";TextBox2.Text = "";

}

protected void Button2Click(object sender, EventArgs e)

{

if (string.IsNullOrEmpty(TextBox1.Text) || string.IsNullOrEmpty(TextBox2.Text))

{

lblResult.Text = "Please Enter Some Values";

lblResult.ForeColor = System.Drawing.Color.Red;

}

else

{

lblResult.Text = "Substraction Result of <b>" + TextBox1.Text + "</b> and <b>" + TextBox2.Text + "</b> is <b>" +_objSubstraction.Arthmetic(Convert.ToDouble(TextBox1.Text), Convert.ToDouble(TextBox2.Text)).ToString(CultureInfo.InvariantCulture) + "</b>";

TextBox1.Text = "";

TextBox2.Text = "";

}

protected void Button3Click(object sender, EventArgs e)

{

if (string.IsNullOrEmpty(TextBox1.Text) || string.IsNullOrEmpty(TextBox2.Text))

{

lblResult.Text = "Please Enter Some Values";

lblResult.ForeColor = System.Drawing.Color.Red;

}

else

{

lblResult.Text = "Multiplication Result of <b>" + TextBox1.Text + "</b> and <b>" + TextBox2.Text + "</b> is <b>" +_objMultiplication.Arthmetic(Convert.ToDouble(TextBox1.Text), Convert.ToDouble(TextBox2.Text)).ToString(CultureInfo.InvariantCulture) + "</b>";TextBox1.Text = "";

TextBox2.Text = "";

}

protected void Button4Click(object sender, EventArgs e)

{

if (string.IsNullOrEmpty(TextBox1.Text) || string.IsNullOrEmpty(TextBox2.Text))

{

lblResult.Text = "Please Enter Some Values";

lblResult.ForeColor = System.Drawing.Color.Red;

}

else

{

lblResult.Text = "Division Result of <b>" + TextBox1.Text + "</b> and <b>" + TextBox2.Text + "</b> is <b>" +_objDivision.Arthmetic(Convert.ToDouble(TextBox1.Text), Convert.ToDouble(TextBox2.Text)).ToString(CultureInfo.InvariantCulture) + "</b>";TextBox1.Text = "";TextBox2.Text = "";

}

#region Private Instance Variablesprivate readonly Addition _objAddition = new Addition();

private readonly Substraction _objSubstraction = new Substraction();

private readonly Multiplication _objMultiplication = new Multiplication();

private readonly Division _objDivision = new Division();#endregion}

}

Step 8: The output of the application looks like this: