TreeView using vb.net

Imports System.IO
Public Class Form1
    Inherits System.Windows.Forms.Form
#Region " Windows Form Designer generated code "
    Public Sub New()
        MyBase.New()
        'This call is required by the Windows Form Designer.
        InitializeComponent()
        'Add any initialization after the InitializeComponent() call
    End Sub
    'Form overrides dispose to clean up the component list.
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub
    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer
    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    Friend WithEvents TreeView1 As System.Windows.Forms.TreeView
    <system.diagnostics.debuggerstepthrough()> Private Sub InitializeComponent()
        Me.TreeView1 = New System.Windows.Forms.TreeView
        Me.SuspendLayout()
        '
        'TreeView1
        '
        Me.TreeView1.Dock = System.Windows.Forms.DockStyle.Fill
        Me.TreeView1.ImageIndex = -1
        Me.TreeView1.Location = New System.Drawing.Point(0, 0)
        Me.TreeView1.Name = "TreeView1"
        Me.TreeView1.SelectedImageIndex = -1
        Me.TreeView1.Size = New System.Drawing.Size(292, 273)
        Me.TreeView1.TabIndex = 0
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(292, 273)
        Me.Controls.Add(Me.TreeView1)
        Me.Name = "Form1"
        Me.Text = "Form1"
        Me.ResumeLayout(False)
    End Sub
#End Region
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim file_name As String = Application.StartupPath
        file_name = file_name.Substring(0, file_name.Length - 1)
        file_name = file_name.Substring(0, file_name.LastIndexOf("\"))
        file_name &= "\test.txt"
        LoadTreeViewFromFile(file_name, TreeView1)
    End Sub
    ' Load a TreeView control from a file that uses tabs
    ' to show indentation.
    Private Sub LoadTreeViewFromFile(ByVal file_name As String, ByVal trv As TreeView)
        ' Get the file's contents.
        Dim stream_reader As New StreamReader(file_name)
        Dim file_contents As String = stream_reader.ReadToEnd()
        stream_reader.Close()
        ' Remove line feeds.
        file_contents = file_contents.Replace(vbLf, "")
        ' Break the file into lines.
        Const charCR As Char = CChar(vbCr)
        Const charTab As Char = CChar(vbTab)
        Dim lines() As String = file_contents.Split(charCR)
        ' Process the lines.
        Dim text_line As String
        Dim level As Integer
        Dim tree_nodes() As TreeNode
        Dim num_nodes As Integer = 0
        ReDim tree_nodes(num_nodes)
        trv.Nodes.Clear()
        For i As Integer = 0 To lines.GetUpperBound(0)
            text_line = lines(i)
            If text_line.Trim().Length > 0 Then
                ' See how many tabs are at the start of the line.
                level = text_line.Length - _
                    text_line.TrimStart(charTab).Length
                ' Make room for the new node.
                If level > num_nodes Then
                    num_nodes = level
                    ReDim Preserve tree_nodes(num_nodes)
                End If
                ' Add the new node.
                If level = 0 Then
                    tree_nodes(level) = trv.Nodes.Add(text_line.Trim() & level)
                Else
                    tree_nodes(level) = tree_nodes(level - 1).Nodes.Add(text_line.Trim() & level)
                End If
                tree_nodes(level).EnsureVisible()
            End If
        Next i
        If trv.Nodes.Count > 0 Then trv.Nodes(0).EnsureVisible()
    End Sub
End Class