existe indice en lista

If flujo.ElementAtOrDefault(i + 1) IsNot Nothing Then

End If

fuente

buscar elemento en una lista

fuente

dataset a lista

Dim ds As New DataSet
Dim list As List(Of Long) = ds.Tables(0).AsEnumerable.Select(Function(x) x.Field(Of Long)(0)).ToList


fuente

ordenar lista de tuplas

Versión 1
Dim elem As New List(Of String)
Dim a As Integer
        Dim b As Integer
        Dim temp As String
        Dim c As Integer = -1
        For i As Integer = 0 To elem.Count - 1
            c += 1
            For j As Integer = c To elem.Count - 1
                a = elem(i).Split(",")(0)
                b = elem(j).Split(",")(0)

                If b < a Then
                    temp = elem(i)
                    elem(i) = elem(j)
                    elem(j) = temp
                End If
            Next
        Next
elem.Clear()

Versión 2
Dim elem As New List(Of String)
 Dim sep As Char = ","
        Dim a As Integer
        Dim b As Integer
        Dim temp As String
        Dim c As Integer = -1
        For i As Integer = 0 To elem.Count - 1
            c += 1
            For j As Integer = c To elem.Count - 1
                a = elem(i).Split(sep)(0)
                b = elem(j).Split(sep)(0)

                If b < a Then
                    temp = elem(i)
                    elem(i) = elem(j)
                    elem(j) = temp
                ElseIf b = a Then
                    a = elem(i).Split(sep)(1)
                    b = elem(j).Split(sep)(1)
                    If b < a Then
                        temp = elem(i)
                        elem(i) = elem(j)
                        elem(j) = temp
                    End If

                End If
            Next
        Next
    elem.Clear()

Cargar un archivo en una lista

Public dataTxt As New List(Of String)
dataTxt = File.ReadAllLines("archivo.txt").ToList()

Transformar un arreglo a List

Dim ruts() As String
Dim listarut As New List(Of String)

listarut = ruts.ToList()
Dim listarut As New List(Of String)(ruts)

Recorrer una lista y arreglo

Dim lista As List(Of String)
        For i As Integer = 0 To lista.Count - 1
            ' Código aquí...
        Next

Dim array() As String
        For j As Integer = 0 To array.Length - 1
            ' Código aquí...
        Next