form 1 vb

Public Class NumericalStatistic
    'Disable buttons if there is no/not enough input'
    Private Sub ValueTextBox_TextChanged(sender As Object, e As EventArgs) Handles ValueTextBox.TextChanged
        ConfirmButton.Enabled = True
        ClearButton.Enabled = True
        'Confirm button disabled if less than 2 input'
        If ValueTextBox.Lines.Length < 2 Then
            ConfirmButton.Enabled = False
        End If
        'Clear Button disabled if no input'
        If ValueTextBox.Text = "" Then
            ClearButton.Enabled = False
        End If
    End Sub

    Private Sub ClearButton_Click(sender As Object, e As EventArgs) Handles ClearButton.Click
        Dim userReply As Integer
        userReply = MsgBox("Are you sure you want to clear?", MsgBoxStyle.Exclamation + MsgBoxStyle.OkCancel, "CLEAR")
        'Clears ValueTextBox if user selects Ok'
        If userReply = MsgBoxResult.Ok Then
            ValueTextBox.Text = ""
        End If
    End Sub

    Private Sub ConfirmButton_Click(sender As Object, e As EventArgs) Handles ConfirmButton.Click
        'Check if input is numeric before moving to the next result form'
        If CheckMultilineTextIsNumeric(ValueTextBox) Then
            AnswerNumericalStatistic.Show()
        End If
    End Sub

    'Function to check wether the input is numeric, remove error lines if user wishes'
    Function CheckMultilineTextIsNumeric(ByRef theTextBox As TextBox) As Boolean
        'Checks user input for non numeric input'
        For i As Integer = 0 To theTextBox.Lines.Length - 1
            If Not IsNumeric(theTextBox.Lines(i).Trim) Then
                Dim userReply As Integer
                userReply = MsgBox("The value text box should contain only numbers!" & vbNewLine & "Do you want to delete the error lines?", MsgBoxStyle.Exclamation + MsgBoxStyle.OkCancel, "ERROR!")

                If userReply = MsgBoxResult.Ok Then
                    Dim dummyTextBox(theTextBox.Lines.Length) As String
                    Dim count As Integer = 0
                    For j As Integer = 0 To theTextBox.Lines.Length - 1
                        If IsNumeric(theTextBox.Lines(j).Trim) Then
                            'Creates an array of user input that doesn't include the input errors
                            dummyTextBox(count) = theTextBox.Lines(j)
                            count += 1
                        End If
                    Next
                    Array.Resize(Of String)(dummyTextBox, count)
                    'resize to get rid of the (will be) empty lines
                    Array.Resize(Of String)(theTextBox.Lines, count)
                    theTextBox.Lines = dummyTextBox
                End If
                Return False
            End If
        Next
        'If no input error'
        Return True
    End Function
End Class