上一节学习了从vs中利用编辑器手动编辑节点，本节主要谈谈使用代码来编辑节点，实际也就是对TreeNode的操作。

先看看窗体中控件的布局：

为了区别根节点和子节点，特地做了点区分。

窗体载入的时候，把ImageList中的图片载入4个ListView中，

ListView的SmallImageList属性设置为ImageList1;View属性设置为SmallIcon：

    Private Sub Form7_Load(sender As Object,e As EventArgs) Handles MyBase.Load
        For i As Integer = 0 To ImageList1.Images.Count - 1
            ListView1.Items.Add(New ListViewItem("",i))
            ListView2.Items.Add(New ListViewItem("",i))
            ListView3.Items.Add(New ListViewItem("",i))
            ListView4.Items.Add(New ListViewItem("",i))
        Next

    End Sub

添加根节点：

    '添加根节点
    Private Sub Button1_Click(sender As Object,e As EventArgs) Handles Button1.Click
        Dim strNodeName As String = TextBox1.Text
        If ListView1.SelectedIndices.Count = 0 OrElse ListView2.SelectedIndices.Count = 0 Then
            MessageBox.Show("未选择根节点图标")
            Exit Sub
        End If

        Dim tnRoot As New TreeNode(strNodeName)
        tnRoot.ImageIndex = ListView1.SelectedIndices(0)
        tnRoot.SelectedImageIndex = ListView2.SelectedIndices(0)

        TreeView1.Nodes.Add(tnRoot)
    End Sub

其中TreeNode的构造函数之一：

然后再增加显示的图标（tnRoot.ImageIndex =……）和选中时候的图标（tnRoot.SelectedImageIndex =……）

同时请注意，判断是否已经在ListView1和ListView2中选择图标的代码：

If ListView2.SelectedIndices.Count = 0 OrElse ListView2.SelectedIndices.Count = 0 Then

@H_301_32@ '删除根节点 Private Sub Button2_Click(sender As Object,e As EventArgs) Handles Button2.Click If IsNothing(TreeView1.SelectedNode) Then Exit Sub Dim tnSelectedNode As TreeNode = TreeView1.SelectedNode If tnSelectedNode.Level = 0 Then TreeView1.Nodes.Remove(tnSelectedNode) Else MessageBox.Show("此按钮只用于删除根节点") End If End Sub

    '清除根节点
    Private Sub Button3_Click(sender As Object,e As EventArgs) Handles Button3.Click
        TreeView1.Nodes.Clear()
    End Sub

    '添加子节点
    Private Sub Button6_Click(sender As Object,e As EventArgs) Handles Button6.Click
        If IsNothing(TreeView1.SelectedNode) Then Exit Sub

        Dim tnSelectedNode As TreeNode = TreeView1.SelectedNode
        If ListView3.SelectedIndices.Count = 0 OrElse ListView4.SelectedIndices.Count = 0 Then
            MessageBox.Show("未选择节点图标")
            Exit Sub
        End If
        Dim strNodeName As String = TextBox2.Text
        Dim tnAddNode As New TreeNode(strNodeName,ListView3.SelectedIndices(0),ListView4.SelectedIndices(0))

        tnSelectedNode.Nodes.Add(tnAddNode)
    End Sub

删除节点：

    '删除普通节点
    Private Sub Button5_Click(sender As Object,e As EventArgs) Handles Button5.Click
        If IsNothing(TreeView1.SelectedNode) Then Exit Sub
        Dim tnSelectedNode As TreeNode = TreeView1.SelectedNode
        If tnSelectedNode.Level <> 0 Then
            TreeView1.Nodes.Remove(tnSelectedNode)
        Else
            MessageBox.Show("此按钮只用于删除普通节点")
        End If
    End Sub

清除子节点：

    '清除当前节点下的所有子节点
    Private Sub Button4_Click(sender As Object,e As EventArgs) Handles Button4.Click
        If IsNothing(TreeView1.SelectedNode) Then Exit Sub
        Dim tnSelectedNode As TreeNode = TreeView1.SelectedNode
        If tnSelectedNode.Nodes.Count > 0 Then
            tnSelectedNode.Nodes.Clear()
        Else
            MessageBox.Show("此节点下没有子节点")
        End If
    End Sub

学习更多vb.net知识，请参看 vb.net 教程 目录