ArrayList is an heterogeneous collection of objects where each object can be indexed individually. While writing an application there could be some scenarios where we have ArrayList object filled with data and we want that data in delimited format using any character (comma in our case). For instance suppose we have multiple email addresses added in ArrayList object and we want to use these email addresses in comma separated form so we can set them to To, Cc and Bcc properties in our email component.

Following code snippet shows how to get ArrayList object in comma separated form.

C# Code Sample

using System;
using System.Collections;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            ArrayList arrayList = new ArrayList();
            
            arrayList.Add("person1@domain.com");
            arrayList.Add("person2@domain.com");
            arrayList.Add("person3@domain.com");

            string commString = String.Join(",", arrayList.ToArray());

            Console.Write("Comma separated string = " + commString);
            Console.ReadKey();
        }
    }
}

VB Code Sample

Module Module1

    Sub Main()
        Dim arrayList As New ArrayList()

        arrayList.Add("person1@domain.com")
        arrayList.Add("person2@domain.com")
        arrayList.Add("person3@domain.com")

        Dim commString As String = [String].Join(",", arrayList.ToArray())

        Console.Write(Convert.ToString("Comma separated string = ") & commString)
        Console.ReadKey()
    End Sub

End Module

Please note you can use other separator in place of comma(",") to separate the strings.