ArrayList Collection on C#

The ArrayList Collection implements the IList Interface and uses an array that is dynamic. The array resized automatically as required and dynamic memory allocation is allowed. The ArrayList Collection is an alternative of arrays.

Constructors in ArrayList Collection

The different constructors and their description is given as follows:

Table: Constructors in ArrayList in C#

Source: MSDN

Properties in ArrayList Collection

The different properties and their description is given as follows:

Table: Properties in ArrayList in C#

Source: MSDN

Methods in ArrayList Collection

The different methods and their description is given as follows:

Table: Methods in ArrayList in C#

Source: MSDN

ArrayList Operations

Some of the SortedList operations are given as follows:

Adding elements in ArrayList

Elements can be added to the ArrayList using the Add() method. It adds the specified values to the ArrayList. The program that demonstrates this is given as follows:

Source Code: Program to add elements in ArrayList in C#

using System;
using System.Collections;
namespace ArrayListDemo
{
  class Example
  {
     static void Main(string[] args)
     {
        ArrayList arr = new ArrayList();
        arr.Add(5);
        arr.Add(1);
        arr.Add(9);
        arr.Add(6);
        arr.Add(2);
        arr.Add(8);
        arr.Add(3);
        arr.Add(7);
        Console.Write("ArrayList elements are: ");
        foreach (int i in arr)
        {
           Console.Write(i + " ");
        }
     }
  }
}

The output of the above program is given below:

ArrayList elements are: 5 1 9 6 2 8 3 7

Deleting elements from ArrayList

An element can be deleted from the ArrayList using the Remove() method. This method deletes the first occurance of the value that is provided. The program that demonstrates this is given as follows:

Source Code: Program to delete elements from ArrayList in C#

using System;
using System.Collections;
namespace ArrayListDemo
{
  class Example
  {
     static void Main(string[] args)
     {
        ArrayList arr = new ArrayList();
        arr.Add(5);
        arr.Add(1);
        arr.Add(9);
        arr.Add(6);
        arr.Add(2);
        arr.Add(8);
        arr.Add(3);
        arr.Add(7);
        Console.Write("Original ArrayList elements: ");
        foreach (int i in arr)
        {
           Console.Write(i + " ");
        }
        arr.Remove(1);
        arr.Remove(8);
        arr.Remove(5);
        Console.WriteLine();
        Console.Write("ArrayList elements after deletion: ");
        foreach (int i in arr)
        {
           Console.Write(i + " ");
        }
     }
  }
}

The output of the above program is given below:

Original ArrayList elements: 5 1 9 6 2 8 3 7
ArrayList elements after deletion: 9 6 2 3 7

Reversing elements in ArrayList

The Reverse() method is used to reverse the order of the ArrayList elements. The program that demonstrates this is given as follows:

Source Code: Program to reverse elements in ArrayList in C#

using System;
using System.Collections;
namespace ArrayListDemo
{
  class Example
  {
     static void Main(string[] args)
     {
        ArrayList arr = new ArrayList();
        arr.Add(5);
        arr.Add(1);
        arr.Add(9);
        arr.Add(6);
        arr.Add(2);
        arr.Add(8);
        arr.Add(3);
        arr.Add(7);
        Console.Write("ArrayList elements: ");
        foreach (int i in arr)
        {
           Console.Write(i + " ");
        }
       // reversing array
        arr.Reverse();
        Console.WriteLine();
        Console.Write("Reversed ArrayList elements: ");
        foreach (int i in arr)
        {
           Console.Write(i + " ");
        }
     }
  }
}

The output of the above program is given below:

ArrayList elements: 5 1 9 6 2 8 3 7
Reversed ArrayList elements: 7 3 8 2 6 9 1 5

Sorting elements in ArrayList

The Sort() method is used to sort the ArrayList elements. The program that demonstrates this is given as follows:

Source Code: Program to sort elements in ArrayList in C#

using System;
using System.Collections;
namespace ArrayListDemo
{
  class Example
  {
     static void Main(string[] args)
     {
        ArrayList arr = new ArrayList();
        arr.Add(5);
        arr.Add(1);
        arr.Add(9);
        arr.Add(6);
        arr.Add(2);
        arr.Add(8);
        arr.Add(3);
        arr.Add(7);
        Console.Write("ArrayList elements: ");
        foreach (int i in arr)
        {
           Console.Write(i + " ");
        }
        arr.Sort();
        Console.WriteLine();
        Console.Write("Sorted ArrayList elements: ");
        foreach (int i in arr)
        {
           Console.Write(i + " ");
        }
     }
  }
}

The output of the above program is given below:

ArrayList elements: 5 1 9 6 2 8 3 7
Sorted ArrayList elements: 1 2 3 5 6 7 8 9

Conversion of ArrayList to Array

To convert an ArrayList to Array, the following is the code:

Source Code: Program to convert an ArrayList to Array in C#

using System;
using System.Collections;
public class Example
{
   public static void Main()
   {
       ArrayList arr = new ArrayList();
       arr.Add("AB");
       arr.Add("BC");
       arr.Add("DE");
       arr.Add("FG");
       arr.Add("HI");
       arr.Add("JK");
       string[] myArr = arr.ToArray(typeof(string)) as string[];
       foreach (string a in myArr)
       {
           Console.WriteLine(a);
       }
   }
}

The above program gives the following output:

AB
BC
DE
FG
HI
JK

Remove an element from an ArrayList at a position specified by user

At times, you may want to delete an element at a particular position in an ArrayList. For that, use the RemoveAt() method:

Source Code: Program to delete an element at a particular position in an ArrayList in C#

using System;  
using System.Collections.Generic;  
public class Example  
{  
   public static void Main(string[] args)  
   {
       var l = new List<string>();  
       l.Add("One");  
       l.Add("Two");  
       l.Add("Three");  
       foreach (var arr in l)  
       {
          Console.WriteLine(arr);  
       }
       l.RemoveAt(1);
       Console.WriteLine("New list after deleting a single element:");
       foreach (var arr in l)  
       {
          Console.WriteLine(arr);  
       }
   }
}

The above program gives the following output:

One
Two
Three
New list after deleting a single element:
One
Three

Check whether the ArrayList has a fixed size or not

Use the IsFixedSize() property in C# to get a value stating whether the ArrayList has a fixed size or not

Let us see an example:

Source Code: Program to check whether the ArrayList has a fixed size or not in C#

using System;
using System.Collections;
namespace ArrayListDemo
{
  class Example
  {
     static void Main(string[] args)
     {
        ArrayList arr = new ArrayList();
        arr.Add(100);
        arr.Add(120);
        arr.Add(90);
        arr.Add(60);
        arr.Add(200);
        arr.Add(110);
        arr.Add(130);
        arr.Add(180);
        arr.Add(195);
        arr.Add(165);
        arr.Add(80);
        Console.Write("ArrayList elements = ");
        foreach (int i in arr)
        {
           Console.Write(i + " ");
        }
        Console.WriteLine("\nIsFixedSize? " + arr.IsFixedSize);
     }
  }
}

The above program gives the following output:

ArrayList elements = 100 120 90 60 200 110 130 180 195 165 80
IsFixedSize? False

Check whether the ArrayList is read only or not

Use the IsFixedSize() property in C# to get a value stating whether the ArrayList is read only or not

Let us see an example:

Source Code: Program to check whether the ArrayList is read only or not in C#

using System;
using System.Collections;
namespace ArrayListDemo
{
  class Example
  {
     static void Main(string[] args)
     {
        ArrayList arr = new ArrayList();
        arr.Add(5);
        arr.Add(1);
        arr.Add(9);
        arr.Add(6);
        arr.Add(2);
        arr.Add(8);
        arr.Add(3);
        arr.Add(7);
        Console.Write("ArrayList elements = ");
        foreach (int i in arr)
        {
           Console.Write(i + " ");
        }
        Console.WriteLine("\nIsReadOnly? " + arr.IsReadOnly);
     }
  }
}

The above program gives the following output:

ArrayList elements = 5 1 9 6 2 8 3 7
IsReadOnly? False

Get the maximum size of the ArrayList

Use the Capacity property to get the maximum size of the ArrayList. Let us now see an example:

Source Code: Program to get the maximum size of the ArrayList in C#

using System;
using System.Collections;
namespace ArrayListDemo
{
  class Example
  {
     static void Main(string[] args)
     {
        ArrayList arr = new ArrayList();
        arr.Add(100);
        arr.Add(120);
        arr.Add(90);
        arr.Add(60);
        arr.Add(200);
        arr.Add(110);
        arr.Add(130);
        arr.Add(180);
        arr.Add(195);
        arr.Add(165);
        arr.Add(80);
        Console.Write("ArrayList elements = ");
        foreach (int i in arr)
        {
           Console.Write(i + " ");
        }
        Console.WriteLine("\nCapacity = " + arr.Capacity);
     }
  }
}

The above program gives the following output:

ArrayList elements = 100 120 90 60 200 110 130 180 195 165 80
Capacity = 16

Count the number of elements in a ArrayList

Use the Count property to count the number of elements in a ArrayList . Let us see an example:

Source Code: Program to count the number of elements in the ArrayList in C#

using System;
using System.Collections;
namespace ArrayListDemo
{
  class Example
  {
     static void Main(string[] args)
     {
        ArrayList arr = new ArrayList();
        arr.Add(100);
        arr.Add(120);
        arr.Add(90);
        arr.Add(60);
        arr.Add(200);
        arr.Add(110);
        arr.Add(130);
        arr.Add(180);
        arr.Add(195);
        arr.Add(165);
        arr.Add(80);
        arr.Add(99);
        arr.Add(145);
        arr.Add(198);
        arr.Add(210);
        Console.Write("ArrayList elements = ");
        foreach (int i in arr)
        {
           Console.Write(i + " ");
        }
        Console.WriteLine("\n\nCount = " + arr.Count);
        Console.WriteLine("Capacity = " + arr.Capacity);
     }
  }
}

The above program gives the following output:

ArrayList elements = 100 120 90 60 200 110 130 180 195 165 80 99 145 198 210
Count = 15
Capacity = 16

Fetch an element at a specified position in ArrayList

At times, you may need to fetch an element at a specified position in ArrayList. For that, the following is the code:

Source Code: Program to fetch an element at a specified position in ArrayList in C#

using System;
using System.Collections;
namespace ArrayListDemo
{
  class Example
  {
     static void Main(string[] args)
     {
        ArrayList arr = new ArrayList();
        arr.Add(100);
        arr.Add(120);
        arr.Add(90);
        arr.Add(60);
        arr.Add(200);
        arr.Add(110);
        arr.Add(130);
        arr.Add(180);
        arr.Add(195);
        arr.Add(165);
        arr.Add(80);
        arr.Add(99);
        arr.Add(145);
        arr.Add(198);
        arr.Add(210);
        Console.Write("ArrayList elements = ");
        foreach (int i in arr)
        {
           Console.Write(i + " ");
        }
        Console.WriteLine("\n\nCount = " + arr.Count);
        Console.WriteLine("Capacity = " + arr.Capacity);
        Console.WriteLine("Element {0} is \"{1}\"", 2+"th", arr[1]);
        Console.WriteLine("Element {0} is \"{1}\"", 4+"th", arr[3]);
        Console.WriteLine("Element {0} is \"{1}\"", 6+"th", arr[5]);
        Console.WriteLine("Element {0} is \"{1}\"", 8+"th", arr[7]);
     }
  }
}

The above program generates the following output:

ArrayList elements = 100 120 90 60 200 110 130 180 195 165 80 99 145 198 210
Count = 15
Capacity = 16
Element 2th is "120"
Element 4th is "60"
Element 6th is "110"
Element 8th is "180"