Uploading Multiple Files With ListBox in ASP.NET

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="UploadFileWithListBox.aspx.cs" Inherits="UploadFileWithListBox" %>  
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">  
<html xmlns="http://www.w3.org/1999/xhtml">  
<head runat="server">  
    <title></title>  
</head>  
<body>  
    <form id="form1" runat="server">  
        <div>  
        </div>  
        <p>  
            <asp:FileUpload ID="FileUpload1" runat="server" />  
        </p>  
        <p>  
            <asp:ListBox ID="ListBox1" runat="server" Rows="5" SelectionMode="Single" Width="221px" BackColor="#CCCCFF">  
            </asp:ListBox>  
            <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>  
        </p>  
        <p>  
            <asp:Button ID="Button1" runat="server" Text="Add" Width="75px" OnClick="Button1_Click" />  
            <asp:Button ID="Button2" runat="server" Text="Remove" Width="98px" OnClick="Button2_Click" />  
        </p>  
    </form>  
</body>  
</html>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;

protected void Button1_Click(object sender, EventArgs e)  
{  
    try  
    {  
        if (FileUpload1.HasFile)  
        {  
            if (FileUpload1.PostedFile.ContentLength > 0)  
            {  
                if (ListBox1.Items.Contains(new ListItem(System.IO.Path.GetFileName(FileUpload1.PostedFile.FileName))))  
                {  
                    Label1.Text = "File already in the ListBox";  
                }  
                else  
                {  
                    Files.Add(FileUpload1);  
                    ListBox1.Items.Add(System.IO.Path.GetFileName(FileUpload1.PostedFile.FileName));  
                    Label1.Text = "Add another file or click Upload to save them all";  
                }  
            }  
            else  
            {  
                Label1.Text = "File size cannot be 0";  
            }  
        }  
        else  
        {  
            Label1.Text = "Please select a file to add";  
        }  
    }  
    catch (Exception ex)  
    {  
        // Handle the exception here (optional)
    }  
}

Some important property.

• FileUpload1.HasFile: The HasFile property gets a value indicating whether the FileUpload control contains a file to upload.
• ContentLength: To find the size of an upload file in bytes.
• FileName: To get the name of the file.

Now double-click on the Remove Button control and write the following code to remove the uploaded file from the ListBox.

protected void Button2_Click(object sender, EventArgs e)  
{  
    if (ListBox1.Items.Count > 0)  
    {  
        if (ListBox1.SelectedIndex < 0)  
        {  
            Label1.Text = "Please select a file to remove";  
        }  
        else  
        {  
            Files.RemoveAt(ListBox1.SelectedIndex);  
            ListBox1.Items.Remove(ListBox1.SelectedItem.Text);  
            Label1.Text = "File removed";  
        }  
    }  
}  

Now the .cs file looks like the following code.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;

public partial class UploadFileWithListBox : System.Web.UI.Page
{
    public static ArrayList Files = new ArrayList();
    protected void Page_Load(object sender, EventArgs e)
    {
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        try
        {
            if (FileUpload1.HasFile) // that the FileUpload control contains a file.
            {
                if (FileUpload1.PostedFile.ContentLength > 0) // Get the size of the upload file.
                {
                    if (ListBox1.Items.Contains(new ListItem(System.IO.Path.GetFileName(FileUpload1.PostedFile.FileName)))) // Get the name of the file to upload.
                    {
                        Label1.Text = "File already in the list";
                    }
                    else
                    {
                        Files.Add(FileUpload1);
                        ListBox1.Items.Add(System.IO.Path.GetFileName(FileUpload1.PostedFile.FileName));
                        Label1.Text = "Add another file or click Upload to save them all";
                    }
                }
                else
                {
                    Label1.Text = "File size cannot be 0";
                }
            }
            else
            {
                Label1.Text = "Please select a file to add";
            }
        }
        catch (Exception ex)
        {
            // Handle the exception
        }
    }
    protected void Button2_Click(object sender, EventArgs e)
    {
        if (ListBox1.Items.Count > 0)
        {
            if (ListBox1.SelectedIndex < 0)
            {
                Label1.Text = "Please select a file to remove";
            }
            else
            {
                Files.RemoveAt(ListBox1.SelectedIndex);
                ListBox1.Items.Remove(ListBox1.SelectedItem.Text);
                Label1.Text = "File removed";
            }
        }
    }
}

Now run the application and test it.

Now upload a file and click on the add Button to add the file in ListBox.

Now add another file or click the add Button.

Now select a file from the ListBox.

Now click on the remove Button to remove the file from the list.