TreeNode Class (System.Windows.Forms)

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TreeNode Class

Represents a node of a TreeView.

Inheritance Hierarchy

System.Object
  System.MarshalByRefObject
    System.Windows.Forms.TreeNode
      System.ComponentModel.Design.ObjectSelectorEditor.SelectorNode
      System.Workflow.ComponentModel.Design.WorkflowOutlineNode

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

Visual Basic
<SerializableAttribute> _
<TypeConverterAttribute(GetType(TreeNodeConverter))> _
Public Class TreeNode _
	Inherits MarshalByRefObject _
	Implements ICloneable, ISerializable
C#
[SerializableAttribute]
[TypeConverterAttribute(typeof(TreeNodeConverter))]
public class TreeNode : MarshalByRefObject, ICloneable, 
	ISerializable
Visual C++
[SerializableAttribute]
[TypeConverterAttribute(typeof(TreeNodeConverter))]
public ref class TreeNode : public MarshalByRefObject, 
	ICloneable, ISerializable
F#
[<SerializableAttribute>]
[<TypeConverterAttribute(typeof(TreeNodeConverter))>]
type TreeNode =  
    class
        inherit MarshalByRefObject
        interface ICloneable
        interface ISerializable
    end

The TreeNode type exposes the following members.

Constructors

  Name Description
Public method TreeNode() Initializes a new instance of the TreeNode class.
Public method TreeNode(String) Initializes a new instance of the TreeNode class with the specified label text.
Protected method TreeNode(SerializationInfo, StreamingContext) Initializes a new instance of the TreeNode class using the specified serialization information and context.
Public method TreeNode(String, TreeNode[]) Initializes a new instance of the TreeNode class with the specified label text and child tree nodes.
Public method TreeNode(String, Int32, Int32) Initializes a new instance of the TreeNode class with the specified label text and images to display when the tree node is in a selected and unselected state.
Public method TreeNode(String, Int32, Int32, TreeNode[]) Initializes a new instance of the TreeNode class with the specified label text, child tree nodes, and images to display when the tree node is in a selected and unselected state.
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Properties

  Name Description
Public property BackColor Gets or sets the background color of the tree node.
Public property Bounds Gets the bounds of the tree node.
Public property Checked Gets or sets a value indicating whether the tree node is in a checked state.
Public property ContextMenu Gets the shortcut menu that is associated with this tree node.
Public property ContextMenuStrip Gets or sets the shortcut menu associated with this tree node.
Public property FirstNode Gets the first child tree node in the tree node collection.
Public property ForeColor Gets or sets the foreground color of the tree node.
Public property FullPath Gets the path from the root tree node to the current tree node.
Public property Handle Gets the handle of the tree node.
Public property ImageIndex Gets or sets the image list index value of the image displayed when the tree node is in the unselected state.
Public property ImageKey Gets or sets the key for the image associated with this tree node when the node is in an unselected state.
Public property Index Gets the position of the tree node in the tree node collection.
Public property IsEditing Gets a value indicating whether the tree node is in an editable state.
Public property IsExpanded Gets a value indicating whether the tree node is in the expanded state.
Public property IsSelected Gets a value indicating whether the tree node is in the selected state.
Public property IsVisible Gets a value indicating whether the tree node is visible or partially visible.
Public property LastNode Gets the last child tree node.
Public property Level Gets the zero-based depth of the tree node in the TreeView control.
Public property Name Gets or sets the name of the tree node.
Public property NextNode Gets the next sibling tree node.
Public property NextVisibleNode Gets the next visible tree node.
Public property NodeFont Gets or sets the font that is used to display the text on the tree node label.
Public property Nodes Gets the collection of TreeNode objects assigned to the current tree node.
Public property Parent Gets the parent tree node of the current tree node.
Public property PrevNode Gets the previous sibling tree node.
Public property PrevVisibleNode Gets the previous visible tree node.
Public property SelectedImageIndex Gets or sets the image list index value of the image that is displayed when the tree node is in the selected state.
Public property SelectedImageKey Gets or sets the key of the image displayed in the tree node when it is in a selected state.
Public property StateImageIndex Gets or sets the index of the image that is used to indicate the state of the TreeNode when the parent TreeView has its CheckBoxes property set to false.
Public property StateImageKey Gets or sets the key of the image that is used to indicate the state of the TreeNode when the parent TreeView has its CheckBoxes property set to false.
Public property Tag Gets or sets the object that contains data about the tree node.
Public property Text Gets or sets the text displayed in the label of the tree node.
Public property ToolTipText Gets or sets the text that appears when the mouse pointer hovers over a TreeNode.
Public property TreeView Gets the parent tree view that the tree node is assigned to.
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Methods

  Name Description
Public method BeginEdit Initiates the editing of the tree node label.
Public method Clone Copies the tree node and the entire subtree rooted at this tree node.
Public method Collapse() Collapses the tree node.
Public method Collapse(Boolean) Collapses the TreeNode and optionally collapses its children.
Public method CreateObjRef Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from MarshalByRefObject.)
Protected method Deserialize Loads the state of the TreeNode from the specified SerializationInfo.
Public method EndEdit Ends the editing of the tree node label.
Public method EnsureVisible Ensures that the tree node is visible, expanding tree nodes and scrolling the tree view control as necessary.
Public method Equals(Object) Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Public method Expand Expands the tree node.
Public method ExpandAll Expands all the child tree nodes.
Protected method Finalize Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public method Static member FromHandle Returns the tree node with the specified handle and assigned to the specified tree view control.
Public method GetHashCode Serves as a hash function for a particular type. (Inherited from Object.)
Public method GetLifetimeService Retrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Public method GetNodeCount Returns the number of child tree nodes.
Public method GetType Gets the Type of the current instance. (Inherited from Object.)
Public method InitializeLifetimeService Obtains a lifetime service object to control the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
Protected method MemberwiseClone() Creates a shallow copy of the current Object. (Inherited from Object.)
Protected method MemberwiseClone(Boolean) Creates a shallow copy of the current MarshalByRefObject object. (Inherited from MarshalByRefObject.)
Public method Remove Removes the current tree node from the tree view control.
Protected method Serialize Saves the state of the TreeNode to the specified SerializationInfo.
Public method Toggle Toggles the tree node to either the expanded or collapsed state.
Public method ToString Returns a string that represents the current object. (Overrides Object.ToString().)
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Explicit Interface Implementations

  Name Description
Explicit interface implemetation Private method ISerializable.GetObjectData Populates a serialization information object with the data needed to serialize the TreeNode.
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Remarks

The Nodes collection holds all the child TreeNode objects assigned to the current TreeNode. You can add, remove, or clone a TreeNode; when you do this, 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 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.

Examples

The following code 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 requires that you have a Customer object that can hold a collection of Order objects. It also requires that you have created an instance of a TreeView control on a Form.

Visual Basic

Public Class Customer
   Inherits [Object]
   Private custName As String = ""
   Friend custOrders As New ArrayList()

   Public Sub New(ByVal customername As String)
      Me.custName = customername
   End Sub

   Public Property CustomerName() As String
      Get
         Return Me.custName
      End Get
      Set(ByVal Value As String)
         Me.custName = Value
      End Set
   End Property

   Public ReadOnly Property CustomerOrders() As ArrayList
      Get
         Return Me.custOrders
      End Get
   End Property
End Class 'End Customer class


Public Class Order
   Inherits [Object]
   Private ordID As String

   Public Sub New(ByVal orderid As String)
      Me.ordID = orderid
   End Sub 'New

   Public Property OrderID() As String
      Get
         Return Me.ordID
      End Get
      Set(ByVal Value As String)
         Me.ordID = Value
      End Set
   End Property
End Class ' End Order class

' 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#


// The basic Customer class.
public class Customer : System.Object
{
   private string custName = "";
   protected ArrayList custOrders = new ArrayList();

   public Customer(string customername)
   {
      this.custName = customername;
   }

   public string CustomerName
   {      
      get{return this.custName;}
      set{this.custName = value;}
   }

   public ArrayList CustomerOrders 
   {
      get{return this.custOrders;}
   }

} // End Customer class 


// The basic customer Order class.
public class Order : System.Object
{
   private string ordID = "";

   public Order(string orderid)
   {
      this.ordID = orderid;
   }

   public string OrderID
   {      
      get{return this.ordID;}
      set{this.ordID = value;}
   }

} // End Order class

// 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();
}


Visual C++

// The basic Customer class.
ref class Customer: public System::Object
{
private:
   String^ custName;

protected:
   ArrayList^ custOrders;

public:
   Customer( String^ customername )
   {
      custName = "";
      custOrders = gcnew ArrayList;
      this->custName = customername;
   }


   property String^ CustomerName 
   {
      String^ get()
      {
         return this->custName;
      }

      void set( String^ value )
      {
         this->custName = value;
      }

   }

   property ArrayList^ CustomerOrders 
   {
      ArrayList^ get()
      {
         return this->custOrders;
      }

   }

};


// End Customer class
// The basic customer Order class.
ref class Order: public System::Object
{
private:
   String^ ordID;

public:
   Order( String^ orderid )
   {
      ordID = "";
      this->ordID = orderid;
   }


   property String^ OrderID 
   {
      String^ get()
      {
         return this->ordID;
      }

      void set( String^ value )
      {
         this->ordID = value;
      }

   }

};
// End Order class



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

   // Add orders to each Customer object in the ArrayList.
   IEnumerator^ myEnum = customerArray->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Customer^ customer1 = safe_cast<Customer^>(myEnum->Current);
      for ( int y = 0; y < 15; y++ )
      {
         customer1->CustomerOrders->Add( gcnew Order( "Order " + y ) );
      }
   }

   // Display a wait cursor while the TreeNodes are being created.
   ::Cursor::Current = gcnew System::Windows::Forms::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.
   myEnum = customerArray->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Customer^ customer2 = safe_cast<Customer^>(myEnum->Current);
      treeView1->Nodes->Add( gcnew 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 = safe_cast<Order^>(myEnum->Current);
         treeView1->Nodes[ customerArray->IndexOf( customer2 ) ]->Nodes->Add( gcnew TreeNode( customer2->CustomerName + "." + order1->OrderID ) );
      }
   }

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

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


Version Information

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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.
See Also

Reference

Other Resources

Community Content

hoodaticus
Suggest Moving Above Comment
The prior comment was written for the WebForms TreeView, but this is a WinForms article.

Joeri Meerdink
Example (default) (StateManegement, TreeView, Functions, ...)
Imports System.Data.SqlClient
Imports System.Data.Common
Imports StateManagement.BL

Partial Class _Default
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not Me.IsPostBack Then
            '1. TreeView (menu opbouwen)
            PopulateTreeview(TreeView1.Nodes)
        End If

        '2. Preferred Theme instellen op basis van een cookie
        'SetThemeByCookie()

    End Sub

    Private Sub PopulateTreeview(ByVal treeviewNodes As TreeNodeCollection)
        For Each category In Product.GetCategories()
            Dim treenode As New TreeNode
            treenode.Text = Server.HtmlEncode(category)
            treenode.Value = category
            treeviewNodes.Add(treenode)
            Me.PopulateSubLevel(treenode)
        Next
    End Sub

    Private Sub PopulateSubLevel(ByVal treenode As TreeNode)
        For Each prod As Product In Product.GetProducts(treenode.Text)
            Dim tn As New TreeNode
            tn.Text = Server.HtmlEncode(prod.Name)
            tn.Value = prod.ProductID
            treenode.ChildNodes.Add(tn)
        Next
    End Sub

    Protected Sub TreeView1_SelectedNodeChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles TreeView1.SelectedNodeChanged
        viewProduct.ProductID = CType(sender, TreeView).SelectedValue
    End Sub


    Protected Sub Page_PreInit(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreInit
        Dim cookie As HttpCookie = Me.Request.Cookies("Theme")
        If Not cookie Is Nothing Then
            Dim Theme As String = cookie.Value
            ddlTheme.Items.FindByValue(Theme).Selected = True
            Page.Theme = Theme
        Else
            Page.Theme = "ThemeDark"
            ddlTheme.Items.FindByValue("ThemeDark").Selected = True
        End If
    End Sub


    Protected Sub ddlTheme_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddlTheme.SelectedIndexChanged
        Dim cookie As New HttpCookie("Theme", ddlTheme.SelectedValue)
        cookie.Expires = Date.Now.AddMinutes(5.0)
        Response.Cookies.Add(cookie)
        Response.Redirect(Request.Url.ToString)

    End Sub
End Class