1. TreeView Control

2. TreeView Control Drill Down interface
Displays information in a hierarchical manner.
Nodes collection:
Root: No parent
Other nodes have a single parent.
Siblings: Children have the same parent.
First Sibling, Last Sibling
TreeNode Editor

3. TreeView Properties TopNode Nodes GetNodeCount(False) SelectedNode
Nodes(Index)
GetNodeCount(False)
SelectedNode
FullPath

4. Display Root Node’s Children
Dim TrNode As TreeNode
For Each TrNode In TreeView1.TopNode.Nodes
MessageBox.Show(TrNode.Text)
MessageBox.Show(TrNode.FullPath)
Nextree
Note: Nodes is a collection of children nodes directly belong to a parent node.

5. Displaying Selected Node’s Information
Private Sub TreeView1_AfterSelect(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterSelect
MessageBox.Show(TreeView1.SelectedNode.Text)
MessageBox.Show(TreeView1.SelectedNode.FullPath())
End Sub

6. Adding a TreeNode Programmatically
Nodes collection’s Add method:
Add(string)
TreeView1.Nodes.Add("Root")
Add(a tree node)
Define a tree node object
Dim myNode As New TreeNode()
myNode.Text = "Root"
TreeView1.Nodes.Add(myNode)

7. TreeView1.Nodes.Add("Root")
TreeView1.Nodes(0).Nodes.Add("Child1")
TreeView1.Nodes(0).Nodes.Add("Child2")
TreeView1.Nodes(0).Nodes.Add("child3")
TreeView1.Nodes(0).Nodes(0).Nodes.Add("GrandC11")
TreeView1.Nodes(0).Nodes(0).Nodes.Add("GrandC12")
TreeView1.Nodes(0).Nodes(1).Nodes.Add("GrandC21")
TreeView1.Nodes(0).Nodes(2).Nodes.Add("GrandC31")
TreeView1.Nodes(0).Nodes(2).Nodes.Add("GrandC32")
TreeView1.Nodes(0).Nodes(2).Nodes(0).Nodes.Add("GGrandC311")

8. Recursive Procedure
A procedure that calls itself.

9. Creating a TreeView of Directories
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim DiskDrive As String = "C:\"
TreeView1.Nodes.Add(DiskDrive)
Call GetFolders(TreeView1.Nodes(0))
End Sub
Private Sub GetFolders(ByVal CurrentFolder As TreeNode)
Dim FolderPath As String
FolderPath = CurrentFolder.Text
Dim folder As String
If Directory.GetDirectories(FolderPath).Length <> 0 Then
For Each folder In Directory.GetDirectories(FolderPath)
Dim newNode As New TreeNode(folder)
CurrentFolder.Nodes.Add(newNode)
Call GetFolders(newNode)
Next
End If

10. Displaying Files in Selected Folder
Private Sub TreeView1_AfterSelect(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterSelect
Dim currDir As String
currDir = TreeView1.SelectedNode.Text
Dim fName As String
ListBox1.Items.Clear()
For Each fName In Directory.GetFiles(currDir)
ListBox1.Items.Add(fName)
Next
End Sub