Treeview nodes shown in listbox

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When a button is clicked (MoveBtn )How do I copy over the items selected in my tree view to a listbox.

private void MoveBtn_Click(object sender, EventArgs e)
{

    Listbox1.Items.Clear();
    foreach (var node in treeView1.Nodes)
    {
        Listbox1.Items.Add(node);
    }
    Listbox1.Show();

}

This code only shows the root, but not the child nodes which are selected. But I want to show the child nodes too -- if possible only the child nodes

What I have tried:

Listbox1.Items.Clear();
foreach (var node in treeView1.Nodes)
{
    Listbox1.Items.Add(node);
}
Listbox1.Show();

Posted 5-May-18 9:26am

Member 13765884

Updated 6-May-18 0:26am

v3

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BillWoodruff 6-May-18 5:57am

The standard WinForm TreeView does not support multiple selection: are you using a 3rd. party TreeView that does ? I doubt it, but I think asking the question is important, here, just in case.

codeprojectddx 6-May-18 10:49am

when you use treeView1.Nodes ,you are getting those root notes .In fact the second level and below notes are not in the treeView1.Nodes.

2 solutions

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Wendelius · Answer 1 · 2018-05-05T10:14:00

Solution 1

In order to copy all the nodes you need a recursion. Consider the following example (sorry about the typos, I don't have a compiler at hand at the moment)

C#

public void Method1() {
   Listbox1.Items.Clear();
   AddNodes(treeView1.SelectedNode, Listbox1);
}

public void AddNodes(TreeNode parentNode, ListBox lb) {
   foreach (var node in parentNode.Nodes) {
      lb.Items.Add(node);
      AddNodes(node, lb);
   }
}

Posted 5-May-18 10:14am

Wendelius

Comments

Member 13765884 5-May-18 17:11pm

sorry, I dont really understand your answer.

private void MoveBtn_Click(object sender, EventArgs e)
{
Listbox1.Items.Clear();
AddNodes(treeView1.SelectedNode, Listbox1);
Listbox1.Show();
}

public void AddNodes(TreeNode parentNode, ListBox lb)
{
foreach (var node in parentNode.Nodes)
{
lb.Items.Add(node);
AddNodes(parentNode, lb);
}
}
I've tried it and am getting an error of

An unhandled exception of type 'System.NullReferenceException' occurred in monitoring and stock management.exe

Additional information: Object reference not set to an instance of an object.

Wendelius 5-May-18 17:51pm

On which line do you get this exception?

Member 13765884 5-May-18 18:17pm

foreach (var node in parentNode.Nodes)

is the line i get the error in

Wendelius 5-May-18 18:05pm

You probably don't have a selected node when MoveBtn is clicked. Try the following

private void MoveBtn_Click(object sender, EventArgs e) {
   Listbox1.Items.Clear();
   if (treeView1.SelectedNode != null) {
      AddNodes(treeView1.SelectedNode, Listbox1);
   }
   Listbox1.Show();
}

BillWoodruff · Answer 2 · 2018-05-06T00:28:00

Note: the Web Ms TreeView offers easy access to all checked TreeNodes: the WinForms TreeView TreeView does not.

So, you need a method to get all the TreeNodes, and then you need to select all the TreeNodes that are checked. This example uses the "classic" stack-based method that Eric Lippert advocates in order to avoid possible stack overflow with recursion:

public IEnumerable<TreeNode> GetNodes(TreeNodeCollection nodes)
{
    var stack = new Stack<TreeNode>();

    foreach (TreeNode node in nodes)
    {
       stack.Push(node);
    }

    while (stack.Count > 0)
    {
        var current = stack.Pop();
        yield return current;

        foreach (TreeNode child in current.Nodes)
        {
            stack.Push(child);
        }
    }
}

Then filter them to find the checked Nodes:

listBox1.Items.Clear();

var checkedNodes = GetNodes(treeView1.Nodes)
    .Where(nd => nd.Checked)
    .OrderBy(nd => nd.Text)  // remove if you don't want sorted 
    .ToArray();

listBox1.Items.AddRange(checkedNodes.ToArray());