How to take Items from List in Visual Basic - vb.net

Question

I am trying to take Items that I have already added to a list.
Dim lista As New List(Of String)
n = 2
i = 0
Do While i < n + 1
Randomize()
a = Int(Rnd() * 4) + 1
If a = 1 Then
lista.Add("1b")
ElseIf a = 2 Then
lista.Add("2b")
ElseIf a = 3 Then
lista.Add("3b")
ElseIf a = 4 Then
lista.Add("4b")
End If
i = i + 1
Loop
Lets imagine that the list i got was {2b,4b,1b}. Now i want to know how to get lets say just 2b from the list as a first Item and then delete it from the list.

Answer 1

This would be a good place to use a Queue(Of ).
Dim item As String
item = queuea.Dequeue
But List(Of ) has an indexer so you can just use it like an array:
Dim item As String
item = lista(0)
' Then remove the first item:
lista.RemoveAt(0)

Answer 2

Use the .net Random class instead of the old VB6 methods. Calling Random.Next(Interger1, Integer2) will return an Integer equal to or greater than Integer1 and less than Integer2. Note that since the values are so limited there is a good chance of having duplicates in the list.
Although multiple ElseIfs will work, a Select Case is easier to read and less typing.
I put the contents of the list in a ListBox so we could see what was going on. I used the Remove method of List(Of T) then rebind the ListBox.
Private lista As New BindingList(Of String)
Private rand As New Random
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
BuildList()
ListBox1.DataSource = lista
End Sub
Private Sub BuildList()
Dim i = 0
Dim a As Integer
Do While i < 3 'since n never changes just use the literal value
a = rand.Next(1, 5)
Select Case a
Case 1
lista.Add("1b")
Case 2
lista.Add("2b")
Case 3
lista.Add("3b")
Case 4
lista.Add("4b")
End Select
i = i + 1
Loop
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 'Remove from list
lista.Remove(ListBox1.SelectedItem.ToString)
End Sub