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TreeNode Class

Represents a node of a TreeView.

For a list of all members of this type, see TreeNode Members.

System.Object
   System.MarshalByRefObject
      System.Windows.Forms.TreeNode

[Visual Basic]
<Serializable>
Public Class TreeNode
   Inherits MarshalByRefObject
   Implements ICloneable, ISerializable
[C#]
[Serializable]
public class TreeNode : MarshalByRefObject, ICloneable,
   ISerializable
[C++]
[Serializable]
public __gc class TreeNode : public MarshalByRefObject,
   ICloneable, ISerializable
[JScript]
public
   Serializable
class TreeNode extends MarshalByRefObject implements
   ICloneable, ISerializable

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Remarks

The Nodes collection holds all the child TreeNode objects assigned to the current TreeNode. You can add, remove, or clone a TreeNode; when doing so, all child tree nodes are added, removed, or cloned. Each TreeNode can contain a collection of other TreeNode objects. This can make it difficult to determine where you are in the TreeView when iterating through the collection. To determine your location in a tree structure, use the FullPath property. The FullPath string can be parsed using the PathSeparator string value to determine where a TreeNode label begins and ends.

The TreeNode label is set by setting the Text property explicitly. The alternative is to create the tree node using one of the TreeNode constructors that has a string parameter that represents the Text property. The label is displayed next to the TreeNode image, if one is displayed.

To display images next to the tree nodes, assign an ImageList to the ImageList property of the parent TreeView control and assign an Image by referencing its index value in the ImageList property. Set the ImageIndex property to the index value of the Image you want to display when the TreeNode is in an unselected state. Likewise, set the SelectedImageIndex property to the index value of the Image you want to display when the TreeNode is selected.

Selecting specific tree nodes and iterating through the Nodes collection can be achieved by using the following property values: FirstNode, LastNode, NextNode, PrevNode, NextVisibleNode, PrevVisibleNode. Assign the TreeNode object returned by one of aforementioned properties to the TreeView.SelectedNode property to select that tree node in the TreeView control.

Tree nodes can be expanded to display the next level of child tree nodes. The user can expand the TreeNode by pressing the plus (+) button next to the TreeNode, if one is displayed, or you can expand the TreeNode by calling the Expand method. To expand all child tree node levels in the Nodes collection, call the ExpandAll method. You can collapse the child TreeNode level by calling the Collapse method, or the user can press the minus (-) button next to the TreeNode, if one is displayed. You can also call the Toggle method to alternate the TreeNode between the expanded and collapsed states.

Tree nodes can optionally display a check box. To display the check boxes, set the CheckBoxes property of the TreeView to true. The Checked property is set to true for tree nodes that are in a checked state.

Example

[Visual Basic, C#, C++] The following example displays customer information in a TreeView control. The root tree nodes display customer names, and the child tree nodes display the order numbers assigned to each customer. In this example, 1,000 customers are displayed with 15 orders each. The repainting of the TreeView is suppressed by using the BeginUpdate and EndUpdate methods, and a wait Cursor is displayed while the TreeView creates and paints the TreeNode objects. This example assumes you have a Customer object that can hold a collection of Order objects. It also assumes that you have created an instance of a TreeView control on a Form.

[Visual Basic] 
' Create a new ArrayList to hold the Customer objects.
Private customerArray As New ArrayList()

Private Sub FillMyTreeView()
   ' Add customers to the ArrayList of Customer objects.
   Dim x As Integer
   For x = 0 To 999
      customerArray.Add(New Customer("Customer" + x.ToString()))
   Next x

   ' Add orders to each Customer object in the ArrayList.
   Dim customer1 As Customer
   For Each customer1 In customerArray
      Dim y As Integer
      For y = 0 To 14
         customer1.CustomerOrders.Add(New Order("Order" + y.ToString()))
      Next y
   Next customer1

   ' Display a wait cursor while the TreeNodes are being created.
   Cursor.Current = New Cursor("MyWait.cur")

   ' Suppress repainting the TreeView until all the objects have been created.
   treeView1.BeginUpdate()

   ' Clear the TreeView each time the method is called.
   treeView1.Nodes.Clear()

   ' Add a root TreeNode for each Customer object in the ArrayList.
   Dim customer2 As Customer
   For Each customer2 In customerArray
      treeView1.Nodes.Add(New TreeNode(customer2.CustomerName))

      ' Add a child TreeNode for each Order object in the current Customer object.
      Dim order1 As Order
      For Each order1 In customer2.CustomerOrders
         treeView1.Nodes(customerArray.IndexOf(customer2)).Nodes.Add( _
    New TreeNode(customer2.CustomerName + "." + order1.OrderID))
      Next order1
   Next customer2

   ' Reset the cursor to the default for all controls.
   Cursor.Current = System.Windows.Forms.Cursors.Default

   ' Begin repainting the TreeView.
   treeView1.EndUpdate()
End Sub 'FillMyTreeView

[C#] 
// Create a new ArrayList to hold the Customer objects.
private ArrayList customerArray = new ArrayList(); 

private void FillMyTreeView()
{
   // Add customers to the ArrayList of Customer objects.
   for(int x=0; x<1000; x++)
   {
      customerArray.Add(new Customer("Customer" + x.ToString()));
   }

   // Add orders to each Customer object in the ArrayList.
   foreach(Customer customer1 in customerArray)
   {
      for(int y=0; y<15; y++)
      {
         customer1.CustomerOrders.Add(new Order("Order" + y.ToString()));    
      }
   }

   // Display a wait cursor while the TreeNodes are being created.
   Cursor.Current = new Cursor("MyWait.cur");
        
   // Suppress repainting the TreeView until all the objects have been created.
   treeView1.BeginUpdate();

   // Clear the TreeView each time the method is called.
   treeView1.Nodes.Clear();

   // Add a root TreeNode for each Customer object in the ArrayList.
   foreach(Customer customer2 in customerArray)
   {
      treeView1.Nodes.Add(new TreeNode(customer2.CustomerName));
          
      // Add a child treenode for each Order object in the current Customer object.
      foreach(Order order1 in customer2.CustomerOrders)
      {
         treeView1.Nodes[customerArray.IndexOf(customer2)].Nodes.Add(
           new TreeNode(customer2.CustomerName + "." + order1.OrderID));
      }
   }

   // Reset the cursor to the default for all controls.
   Cursor.Current = Cursors.Default;

   // Begin repainting the TreeView.
   treeView1.EndUpdate();
}

[C++] 
void FillMyTreeView() {
    // Add customers to the ArrayList of Customer objects.
    for (int x=0; x<1000; x++) {
        customerArray->Add(new Customer(String::Concat(S"Customer ", __box(x))));
    }

    // Add orders to each Customer object in the ArrayList.
    IEnumerator* myEnum = customerArray->GetEnumerator();
    while (myEnum->MoveNext()) {
        Customer* customer1 = __try_cast<Customer*>(myEnum->Current);

        for (int y=0; y<15; y++) {
            customer1->CustomerOrders->Add(new Order(String::Concat(S"Order ", __box(y))));
        }
    }

    // Display a wait cursor while the TreeNodes are being created.
    Cursor::Current = new System::Windows::Forms::Cursor(S"MyWait.cur");

    // Suppress repainting the TreeView until all the objects have been created.
    treeView1->BeginUpdate();

    // Clear the TreeView each time the method is called.
    treeView1->Nodes->Clear();

    // Add a root TreeNode for each Customer object in the ArrayList.
    while (myEnum->MoveNext()) {
        Customer* customer2 = __try_cast<Customer*>(myEnum->Current);

        treeView1->Nodes->Add(new TreeNode(customer2->CustomerName));

        // Add a child treenode for each Order object in the current Customer object.
        IEnumerator* myEnum = customer2->CustomerOrders->GetEnumerator();
        while (myEnum->MoveNext()) {
            Order* order1 = __try_cast<Order*>(myEnum->Current);

            treeView1->Nodes->Item[customerArray->IndexOf(customer2)]->Nodes->Add(
                new TreeNode(String::Concat(customer2->CustomerName, S".", order1->OrderID)));
        }
    }

    // Reset the cursor to the default for all controls.
    Cursor::Current = Cursors::Default;

    // Begin repainting the TreeView.
    treeView1->EndUpdate();
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.Windows.Forms

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

Assembly: System.Windows.Forms (in System.Windows.Forms.dll)

See Also

TreeNode Members | System.Windows.Forms Namespace | TreeView | TreeNodeCollection

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