Отсортировать массив по возрастанию

Public Class Form1
    Dim A(20) As Integer
    Dim i, j As Integer
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Dim i As Integer
        TextBox1.Text = ""
        For i = 0 To 19
            A(i) = 8 * Rnd() + 1
        Next
        Array.Sort(A)
        For i = 0 To 19
            TextBox1.Text = TextBox1.Text + " " + CStr(A(i))
        Next
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim i, j As Integer
        TextBox2.Text = ""
        For i = 0 To 19
            For j = 0 To 19
                If A(i) = A(j) Then
                    TextBox2.Text = TextBox2.Text + " " + CStr(A(i))
                End If
            Next
        Next
    End Sub
End Class

Public Class Form1
 
  Dim A(20) As Integer
  Dim i, j As Integer
  Dim r As New Random
 
  Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
    Dim i As Integer
    For i = 0 To 19
      A(i) = r.Next(0, 10) '8 * Rnd() + 1
    Next
    Array.Sort(A)
    TextBox1.Text = ""
    For i = 0 To 19
      TextBox1.Text = TextBox1.Text + " " + CStr(A(i))
    Next
  End Sub
 
  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    Dim i, j As Integer
    TextBox2.Text = ""
    For i = 0 To 18
      For j = i + 1 To 19
        If A(i) = A(j) Then
          TextBox2.Text = TextBox2.Text + " " + CStr(A(i))
        End If
      Next
    Next
  End Sub
End Class

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim i As Integer, L As New List(Of Integer)
        TextBox2.Clear()
        For i = 0 To 18
            If L.Contains(A(i)) = False AndAlso Array.LastIndexOf(A, A(i)) > i Then
                L.Add(A(i))
                TextBox2.Text += CStr(A(i)) + " "
            End If
        Next
' для создания массива можно использовать: Dim Mas=L.ToArray
' Формирование содержимого текстового поля осуществлять в отдельном цикле по элементам массива Mas
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim i As Integer, L(9) As Integer, Count As Integer = -1
        TextBox2.Clear()
        For i = 0 To 18
            If (Count = -1 OrElse L.Contains(A(i)) = False) AndAlso Array.LastIndexOf(A, A(i)) > i Then
                Count += 1
                L(Count) = A(i)
            End If
        Next
        For i = 0 To Count
            TextBox2.Text += CStr(L(i)) + " "
        Next
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim i As Integer, L() As Integer = Nothing, Count As Integer = -1
        TextBox2.Clear()
        For i = 0 To 18
            If (Count = -1 OrElse L.Contains(A(i)) = False) AndAlso Array.LastIndexOf(A, A(i)) > i Then
                Count += 1
                ReDim Preserve L(Count)
                L(Count) = A(i)
            End If
        Next
        For i = 0 To Count
            TextBox2.Text += CStr(L(i)) + " "
        Next
    End Sub