directory and file. access files in a directory name space: system.io the directory and file classes...

Directory and File

Access Files in a Directory

• Name space: System.IO

• The Directory and File classes contain only shared methods that set or return information about entries in the file system.

• Shared methods can be called without instantiating an object of that class.

Directory Class

• Methods:– SetCurrentDirectory

• Dim currDir As String = "c:\inetpub\mailroot\drop" Directory.SetCurrentDirectory(currDir)

– GetDirectories: Returns an array of sub directory names in the current directory

• Directory.GetDirectories(currDir)

– GetFiles: Returns an array of file names• Directory.GetFiles(currDir, "*.eml")

GetDirectory Example

Dim currDir As String = "C:\teaching"

Directory.SetCurrentDirectory(currDir)

Dim results As String

Dim folder As String

For Each folder In Directory.GetDirectories(currDir)

results = results & folder & vbCrLf

Next

MessageBox.Show(results)

File Class

• Methods:– GetCreationTime– GetLastAccessTime– GetLastWriteTime– GetAttributes

Dim currDir As String = "c"

Directory.SetCurrentDirectory(currDir)

Dim nFile As Integer

nFile = Directory.GetFiles(currDir).GetUpperBound(0)

Dim fName, fPath As String

For Each fName In Directory.GetFiles(currDir, "*.txt")

ListBox1.Items.Add(fName)

ListBox1.Items.Add(File.GetCreationTime(fName).ToLongDateString())

ListBox1.Items.Add(File.GetLastAccessTime(fName).ToLongDateString)

ListBox1.Items.Add(File.GetLastWriteTime(fName).ToLongDateString)

Next

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

TreeView Properties

• TopNode

• Nodes– Nodes(Index)

• GetNodeCount(False)

• SelectedNode– FullPath

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.

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

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)

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")

Recursive Procedure

• A procedure that calls itself.

Creating a TreeView of DirectoriesPrivate 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

End Sub

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