如何获取 .NET 中 TreeView 中所有子节点的列表
我的 WinForms .NET 应用程序中有一个 TreeView 控件,该控件具有多个级别的子节点,这些子节点具有更多子节点,但没有定义的深度。 当用户选择任何父节点(不一定在根级别)时,如何获取该父节点下的所有节点的列表?
例如,我从这个开始:
Dim nodes As List(Of String)
For Each childNodeLevel1 As TreeNode In parentNode.Nodes
For Each childNodeLevel2 As TreeNode In childNodeLevel1.Nodes
For Each childNodeLevel3 As TreeNode In childNodeLevel2.Nodes
nodes.Add(childNodeLevel3.Text)
Next
Next
Next
问题是这个循环深度是定义的,我只将节点埋入三层。 如果下次用户选择父节点时,有七个级别怎么办?
I have a TreeView control in my WinForms .NET application that has multiple levels of childnodes that have childnodes with more childnodes, with no defined depth. When a user selects any parent node (not necessarily at the root level), how can I get a list of all the nodes beneith that parent node?
For example, I started off with this:
Dim nodes As List(Of String)
For Each childNodeLevel1 As TreeNode In parentNode.Nodes
For Each childNodeLevel2 As TreeNode In childNodeLevel1.Nodes
For Each childNodeLevel3 As TreeNode In childNodeLevel2.Nodes
nodes.Add(childNodeLevel3.Text)
Next
Next
Next
The problem is that this loop depth is defined and I'm only getting nodes burried down three levels. What if next time the user selects a parent node, there are seven levels?
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这是我用来从核心库执行此任务的代码片段。
它允许您以深度优先或呼吸优先的方式列出节点,而无需使用递归,而递归会产生在 JIT 引擎中构造堆栈帧的开销。 它的速度非常快。
要使用它,只需执行以下操作:
List< TreeNode > nodes = TreeViewUtils.FlattenDepth(tree);
抱歉,您有一个 VB.Net 标签; 我无法举出例子,但我相信你会解决的。
public class TreeViewUtils
{
/// <summary>
/// This static utiltiy method flattens all the nodes in a tree view using
/// a queue based breath first search rather than the overhead
/// of recursive method calls.
/// </summary>
/// <param name="tree"></param>
/// <returns></returns>
public static List<TreeNode> FlattenBreath(TreeView tree) {
List<TreeNode> nodes = new List<TreeNode>();
Queue<TreeNode> queue = new Queue<TreeNode>();
//
// Bang all the top nodes into the queue.
//
foreach(TreeNode top in tree.Nodes) {
queue.Enqueue(top);
}
while(queue.Count > 0) {
TreeNode node = queue.Dequeue();
if(node != null) {
//
// Add the node to the list of nodes.
//
nodes.Add(node);
if(node.Nodes != null && node.Nodes.Count > 0) {
//
// Enqueue the child nodes.
//
foreach(TreeNode child in node.Nodes) {
queue.Enqueue(child);
}
}
}
}
return nodes;
}
/// <summary>
/// This static utiltiy method flattens all the nodes in a tree view using
/// a stack based depth first search rather than the overhead
/// of recursive method calls.
/// </summary>
/// <param name="tree"></param>
/// <returns></returns>
public static List<TreeNode> FlattenDepth(TreeView tree) {
List<TreeNode> nodes = new List<TreeNode>();
Stack<TreeNode> stack = new Stack<TreeNode>();
//
// Bang all the top nodes into the queue.
//
foreach(TreeNode top in tree.Nodes) {
stack.Push(top);
}
while(stack.Count > 0) {
TreeNode node = stack.Pop();
if(node != null) {
//
// Add the node to the list of nodes.
//
nodes.Add(node);
if(node.Nodes != null && node.Nodes.Count > 0) {
//
// Enqueue the child nodes.
//
foreach(TreeNode child in node.Nodes) {
stack.Push(child);
}
}
}
}
return nodes;
}
}
阿德里安的方法太棒了。 工作速度相当快并且比递归方法工作得更好。 我已经完成了VB 的翻译。 我从中学到了很多东西。 希望有人仍然需要它。
简单地使用它:
Dim FlattenedNodes As List(Of TreeNode) = clTreeUtil.FlattenDepth(Me.TreeView1)
这是代码,干杯! :
Public Class clTreeUtil
''' <summary>
''' This static utiltiy method flattens all the nodes in a tree view using
''' a queue based breath first search rather than the overhead
''' of recursive method calls.
''' </summary>
''' <param name="tree"></param>
''' <returns></returns>
Public Shared Function FlattenBreath(Tree As TreeView) As List(Of TreeNode)
Dim nodes As List(Of TreeNode) = New List(Of TreeNode)
Dim queue As Queue(Of TreeNode) = New Queue(Of TreeNode)
''
'' Bang all the top nodes into the queue.
''
For Each top As TreeNode In Tree.Nodes
queue.Enqueue(top)
Next
While (queue.Count > 0)
Dim node As TreeNode = queue.Dequeue()
If node IsNot Nothing Then
''
'' Add the node to the list of nodes.
''
nodes.Add(node)
If node.Nodes IsNot Nothing And node.Nodes.Count > 0 Then
''
'' Enqueue the child nodes.
''
For Each child As TreeNode In node.Nodes
queue.Enqueue(child)
Next
End If
End If
End While
Return nodes
End Function
''' <summary>
''' This static utiltiy method flattens all the nodes in a tree view using
''' a stack based depth first search rather than the overhead
''' of recursive method calls.
''' </summary>
''' <param name="tree"></param>
''' <returns></returns>
Public Shared Function FlattenDepth(tree As TreeView) As List(Of TreeNode)
Dim nodes As List(Of TreeNode) = New List(Of TreeNode)
Dim stack As Stack(Of TreeNode) = New Stack(Of TreeNode)
''
'' Bang all the top nodes into the queue.
''
For Each top As TreeNode In tree.Nodes
stack.Push(top)
Next
While (stack.Count > 0)
Dim node As TreeNode = stack.Pop()
If node IsNot Nothing Then
''
'' Add the node to the list of nodes.
''
nodes.Add(node)
If node.Nodes IsNot Nothing And node.Nodes.Count > 0 Then
''
'' Enqueue the child nodes.
''
For Each child As TreeNode In node.Nodes
stack.Push(child)
Next
End If
End If
End While
Return nodes
End Function
End Class
我已将代码转换为 VB.Net,结果如下:
Public Function FlattenBreadth(ByVal tree As TreeView) As List(Of TreeNode)
Dim nodes As New List(Of TreeNode)
Dim queue As New Queue(Of TreeNode)
Dim top As TreeNode
Dim nod As TreeNode
For Each top In tree.Nodes
queue.Enqueue(top)
Next
While (queue.Count > 0)
top = queue.Dequeue
nodes.Add(top)
For Each nod In top.Nodes
queue.Enqueue(nod)
Next
End While
FlattenBreadth = nodes
End Function
如果有人仍然想使用递归方法,使用 Jop 的代码,并保留 TreeNodes(这样你就可以使用它们的 .tag、.name、.checked 或 .text 属性),这是我的版本
Public Shared Function GetChildren(objTree As TreeView) As List(Of TreeNode)
Dim nodes As List(Of TreeNode) = New List(Of TreeNode)
For Each parentNode As TreeNode In objTree.Nodes
nodes.Add(parentNode)
GetAllChildren(parentNode, nodes)
Next
Return nodes
End Function
Public Shared Sub GetAllChildren(parentNode As TreeNode, nodes As List(Of TreeNode))
For Each childNode As TreeNode In parentNode.Nodes
nodes.Add(childNode)
GetAllChildren(childNode, nodes)
Next
End Sub
在 .Net WindowsForm TreeView 中,具有带有可选标志 'searchAllChildren'
的 Find()
方法。
在 asp.net 中却没有。
为了获得相同的结果,我使用这个(类似于 Keith 答案,但在输入中我使用 TreeView)
public static IEnumerable<TreeNode> DescendantNodes2(this TreeView input)
{
foreach (TreeNode node in input.Nodes)
{
yield return node;
foreach (var subnode in node.DescendantNodes())
yield return subnode;
}
}
private static IEnumerable<TreeNode> DescendantNodes(this TreeNode input)
{
foreach (TreeNode node in input.ChildNodes)
{
yield return node;
foreach (var subnode in node.DescendantNodes())
yield return subnode;
}
}
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使用递归
Use recursion