An Overview of SortedList Functionality using Csharp and ASP.NET

Introduction:

SortedList work in same way as List works, the difference is that it keeps the keys always sorted. The SortedList provide binary search to search a data without writing whole code for search.

This article will cover the following topics:

SortedList - Add Item
SortedList - Delete Item
SortedList - Search by Key
SortedList - Search by Value
SortedList - Display Data
SortedList - Other Functionality

Figure 1: Initial UI and SortedList with Month Data

ASP.NET Script:

ASP.NET script is used to properly demonstrate the SortedList functionality. The below script have the following items:

ASP.NET TextBox Controls
ASP.NET Label Controls
ASP.NET Buttons Controls

Listing 1: ASP.NET Script for SortedList Demonstration

<head runat="server">
    <title>MrBool.com - SortedList Tutorial</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        ListItem:
        <asp:TextBox ID="txtListKey" runat="server"></asp:TextBox> 
        <asp:TextBox ID="txtListValue" runat="server"></asp:TextBox>
        <br />
        <br />
        Message:
        <asp:Label ID="lblDisplay" runat="server" Text=""></asp:Label>
        <br />
        <br />
        SortedList State:
        <asp:Label ID="lblSortedListState" runat="server" Text=""></asp:Label>
        <br />
        <br />
         <asp:Button ID="btnAdd" runat="server" Text="Add" OnClick="btnAdd_Click" />
         <asp:Button ID="btnDelete" runat="server" Text="Delete" OnClick="btnDelete_Click" />
         <asp:Button ID="btnSearchbyKey" runat="server" Text="Search by Key" OnClick="btnSearchbyKey_Click" />
         <asp:Button ID="btnSearchbyValue" runat="server" Text="Search by Value" OnClick="btnSearchbyValue_Click" />
    </div>
    </form>
</body>

C# Code:

C# provide a SortedList class and methods to handle the operations of SortedList. Lets start with including the namespace for this.

using System;
using System.Collections.Generic;

Now create the SortedList by

static SortedList<int, string> MonthSortedList;

Now initialize it by

MonthSortedList = new SortedList<int, string>();

The above initializations says that the SortedList is type of , it means key is type of int and value is type of string.

Also you have to load some initial data on page load to perform some operation:

Listing 2: SortedList - Initial Data

           //add the items in sortedlist
            MonthSortedList.Add(1, "Jan");
            MonthSortedList.Add(2, "Feb");
            MonthSortedList.Add(3, "Mar");
            MonthSortedList.Add(4, "Apr");
            MonthSortedList.Add(5, "May");
            MonthSortedList.Add(6, "Jun");

SortedList - Add Item:

Similar to other collection classes SortedList also use Add() method to add the key and value pair. Just pass the both the pairs and and will be added at sorted location.

Figure 2: Add Item - A Key, Value Pair Added (12, “Dec”)

Listing 3: SortedList - Add Item Source Code

protected void btnAdd_Click(object sender, EventArgs e)
    {
        int intKey;
        Int32.TryParse(txtListKey.Text, out intKey);

        if (intKey >= 0 && txtListValue.Text.Trim() != "")
        {
            if (!MonthSortedList.ContainsKey(intKey))
            {
                MonthSortedList.Add(intKey, txtListValue.Text.Trim());

                lblDisplay.Text = "SortedList Item Added";
            }
            else
            {
                lblDisplay.Text = "SortedList - Key Already Exist";
            }
        }
        else
        {
            lblDisplay.Text = "SortedList - Please Enter an Item to Add";
        }
        RenderDetails();
    }

SortedList - Delete Item:

To delete an item from SortedList use the Remove() method. Pass the key in this method and it will delete the item from SortedList. After deletion the List values will be sorted automatically.

Note that for deletion you can use RemoveAt() method also. This method delete the items by index.

Figure 3: Delete Item - (2,”Feb”) is removed from SortedList

Listing 4: SortedList - Delete Item Code

protected void btnDelete_Click(object sender, EventArgs e)
    {
        int intKey;
        Int32.TryParse(txtListKey.Text, out intKey);

        if (intKey >= 0)
        {
            if (MonthSortedList.ContainsKey(intKey))
            {
                MonthSortedList.Remove(intKey);

                //MonthSortedList.RemoveAt(1);
                lblDisplay.Text = "SortedList Item Deleted";
            }
            else
            {
                lblDisplay.Text = "Item Not Found.";
            }
        }
        else
        {
            lblDisplay.Text = "SortedList - Please Enter an Item to Delete";
        }
        RenderDetails();
    }

SortedList - Search by Key:

SortedList provide search by both key also. To search by key use ContainsKey() method and pass the key in it.

Figure 4: Search by Key - The ‘4 -Apr’ found in SortedList key

Listing 5: SortedList - Search by Key - Code

protected void btnSearchbyKey_Click(object sender, EventArgs e)
    {
        int intKey;
        Int32.TryParse(txtListKey.Text, out intKey);

        if (intKey > -1)
        {
            if (MonthSortedList.ContainsKey(intKey))
            {
                lblDisplay.Text = "SortedList Item Found";
            }
            else
            {
                lblDisplay.Text = "SortedList Item Not Found.";
            }
        }
        else
        {
            lblDisplay.Text = "Please Enter an Item to Search";
        }
        RenderDetails();
    }

SortedList - Search by Value:

Use ContainsValue to search a value in the SortedList. This method remove extra effort to loop through all the values and search an item.

Figure 5: Search by Value - The value ‘5-May’ found in SortedList

Listing 6: SortedList - Search by Value - Code

protected void btnSearchbyValue_Click(object sender, EventArgs e)
    {
        if (txtListValue.Text.Trim() != "")
        {
            if (MonthSortedList.ContainsValue(txtListValue.Text.Trim()))
            {
                lblDisplay.Text = "SortedList Item Found";
            }
            else
            {
                lblDisplay.Text = "SortedList Item Not Found.";
            }
        }
        else
        {
            lblDisplay.Text = "Please Enter an Item to Search";
        }
        RenderDetails();
    }

SortedList - Display Data:

The foreach loop is best idea to loop through the items of SortedList and display in an ASP label.

Listing 7: SortedList - Loop through items and display data on ASP page

private void RenderDetails()
    {
        lblSortedListState.Text = "";

        foreach (KeyValuePair<int, string> pair in MonthSortedList)
        {
            lblSortedListState.Text += "," + pair.Key + ":" + pair.Value;
        }
        lblSortedListState.Text = lblSortedListState.Text.TrimStart(',');
    }

SortedList - Other Functionality:

Apart from above functionalities C# SortedList provide some more common functions.

IndexOfKey: Returns the index of a given key.
IndexOfValue: Returns the index of a given value.
Count: Returns the item count
Clear(): Clear the items of SortedList
Capacity : Returns the capacity of SortedList.

Listing 8: SortedList - Other operation

 
private void OtherFunctionality()
    {
        int intKey = 0;
        Int32.TryParse(txtListKey.Text, out intKey);

        lblDisplay.Text = " Get the index of Key: " + MonthSortedList.IndexOfKey(intKey);

        lblDisplay.Text = " Get the index of Value: " + MonthSortedList.IndexOfValue(txtListValue.Text.Trim());

        //Clear all the items of SortedList
        MonthSortedList.Clear();

        lblDisplay.Text = " Count of All the Items of SortedList: " + MonthSortedList.Count;

        lblDisplay.Text = " Capacity of All the Items of SortedList: " + MonthSortedList.Capacity;

    }

Conclusion:

The SortedList is useful on case by case basis, So first find the requirement and then decide which collection to use . I covered almost all common fetures, Please comment here in case you have any queries or doubts.

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