Use ArrayList.Contains to check if a object already exists : ArrayList « Collections « VB.Net Tutorial

1. VB.Net Tutorial
2. Collections
3. ArrayList

Imports System.Collections
Structure Person
    Dim strLastName As String
    Dim strFirstName As String
    Dim strPhone As String
    Dim strEMail As String
End Structure


public class Test
   public Shared Sub Main
        Dim alPersons As New ArrayList
        Dim udtPerson As New Person

        'Add the first person.
        With udtPerson
            .strLastName = "S"
            .strFirstName = "J"
            .strPhone = "5"
            .strEMail = "j@s.com"
        End With
        alPersons.Add(udtPerson)

        'Add the second person.
        With udtPerson
            .strLastName = "J"
            .strFirstName = "S"
            .strPhone = "5"
            .strEMail = "s@s.com"
        End With
        alPersons.Add(udtPerson)

        'Create the third person.
        With udtPerson
            .strLastName = "J"
            .strFirstName = "K"
            .strPhone = "5"
            .strEMail = "k@s.com"
        End With

        'Insert the third person, but first check if they already exists.
        If Not alPersons.Contains(udtPerson) Then
            alPersons.Insert(1, udtPerson)
        End If

        'Remove the first person.
        alPersons.RemoveAt(0)

        'Display the array list values.
        Console.WriteLine("The array list contains " & alPersons.Count & " elements.")
        For Each udtPerson In alPersons
            Console.WriteLine("NAME: " & udtPerson.strFirstName & " " & udtPerson.strLastName)
        Next udtPerson



   End Sub
End class

The array list contains 2 elements.
NAME: K J
NAME: S J