VB.Net - ArrayList Class

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It represents an ordered collection of an object that can be indexed individually. It is basically an alternative to an array. However, unlike array, you can add and remove items from a list at a specified position using an index and the array resizes itself automatically. It also allows dynamic memory allocation, adding, searching and sorting items in the list.

Properties and Methods of the ArrayList Class

The following table lists some of the commonly used properties of the ArrayList class:

PropertyDescription
Capacity Gets or sets the number of elements that the ArrayList can contain.
CountGets the number of elements actually contained in the ArrayList.
IsFixedSizeGets a value indicating whether the ArrayList has a fixed size.
IsReadOnlyGets a value indicating whether the ArrayList is read-only.
ItemGets or sets the element at the specified index.

The following table lists some of the commonly used methods of the ArrayList class:

S.N.Method Name & Purpose
1Public Overridable Function Add ( value As Object ) As Integer
Adds an object to the end of the ArrayList.
2Public Overridable Sub AddRange ( c As ICollection )
Adds the elements of an ICollection to the end of the ArrayList.
3Public Overridable Sub Clear
Removes all elements from the ArrayList.
4Public Overridable Function Contains ( item As Object ) As Boolean
Determines whether an element is in the ArrayList.
5Public Overridable Function GetRange ( index As Integer, count As Integer ) As ArrayList
Returns an ArrayList, which represents a subset of the elements in the source ArrayList.
6Public Overridable Function IndexOf ( value As Object ) As Integer
Returns the zero-based index of the first occurrence of a value in the ArrayList or in a portion of it.
7Public Overridable Sub Insert ( index As Integer, value As Object )
Inserts an element into the ArrayList at the specified index.
8Public Overridable Sub InsertRange ( index As Integer, c As ICollection )
Inserts the elements of a collection into the ArrayList at the specified index.
9Public Overridable Sub Remove ( obj As Object )
Removes the first occurrence of a specific object from the ArrayList.
10Public Overridable Sub RemoveAt ( index As Integer )
Removes the element at the specified index of the ArrayList.
11Public Overridable Sub RemoveRange ( index As Integer, count As Integer )
Removes a range of elements from the ArrayList.
12Public Overridable Sub Reverse
Reverses the order of the elements in the ArrayList.
13Public Overridable Sub SetRange ( index As Integer, c As ICollection )
Copies the elements of a collection over a range of elements in the ArrayList.
14Public Overridable Sub Sort
Sorts the elements in the ArrayList.
15Public Overridable Sub TrimToSize
Sets the capacity to the actual number of elements in the ArrayList.

Example:

The following example demonstrates the concept:

   Sub Main()
      Dim al As ArrayList = New ArrayList()
      Dim i As Integer
      Console.WriteLine("Adding some numbers:")
      al.Add(45)
      al.Add(78)
      al.Add(33)
      al.Add(56)
      al.Add(12)
      al.Add(23)
      al.Add(9)
      Console.WriteLine("Capacity: {0} ", al.Capacity)
      Console.WriteLine("Count: {0}", al.Count)
      Console.Write("Content: ")
      For Each i In al
          Console.Write("{0} ", i)
      Next i
      Console.WriteLine()
      Console.Write("Sorted Content: ")
      al.Sort()
      For Each i In al
          Console.Write("{0} ", i)
      Next i
      Console.WriteLine()
      Console.ReadKey()
   End Sub
End Module

When the above code is compiled and executed, it produces the following result:

Adding some numbers:
Capacity: 8
Count: 7
Content: 45 78 33 56 12 23 9
Content: 9 12 23 33 45 56 78    


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