CODEWITHSUNDEEP
c#treeview
user3904868
user3904868

Reputation:

Pass generic parameter for Treeview & TreeNode

I have the following two methods which loop either a TreeView or TreeNode which I want to combine into a single method. Instead of passing the TreeView/TreeNode I could pass an Object and check the type but wanted to know if there was better way?

private TreeNode SearchNode(string nodetext, TreeNode node)
{
    foreach (TreeNode nd in node.Nodes)
    {
        if (nd.Text == nodetext)
        {
            return nd;
        }
    }
    return null;
}

private TreeNode SearchParentNode(string nodetext, TreeView trv)
{
    foreach (TreeNode node in trv.Nodes)
    {
        if (node.Text == nodetext)
        {
            return node;
        }
    }
    return null;
}

Upvotes: 3

Views: 1523

Answers (3)

Siamak Ferdos
Siamak Ferdos

Reputation: 3299

private TreeNode SearchNode(string nodetext, object obj)
{
    if(obj.GetType() Is TreeView)
    {
          t = (TreeView)obj;
          foreach (TreeView tv in obj.Nodes)
          {
             if (tv.Text == nodetext)
             {
                 return nd;
             }
          }
    }
    else
    {
          n = (TreeNode)obj;
          foreach (TreeNode nd in obj.Nodes)
          {
              if (nd.Text == nodetext)
              {
                 return nd;
              }
          }
    }
    return null;
}

Upvotes: 0

Hans Passant
Hans Passant

Reputation: 941585

Data structures that resemble a tree are best searched using a recursive algorithm. Which could look like:

    public static TreeNode SearchNode(string tofind, TreeNodeCollection nodes) {
        foreach (TreeNode node in nodes) {
            if (node.Text == tofind) return node;
            var nested = SearchNode(tofind, node.Nodes);
            if (nested != null) return nested;
        }
        return null;
    }

Sample usage:

    var node = SearchNode("foo", treeView1.Nodes);
    if (node != null) {
        node.Expand();
        node.EnsureVisible();
    }

Note how this works for any TreeView, not just one that's limited to a single parent-child relationship. It is a depth-first search, locating the first string in the order the user sees them on the screen.

Upvotes: 2

Grant Winney
Grant Winney

Reputation: 66449

You want a single method that can search for a value in a NodesCollection, so just extract the contents of both methods into a single, third method that accepts a NodesCollection:

private TreeNode SearchNodes(string nodeText, TreeNodesCollection nodes)
{
    foreach (TreeNode node in nodes)
    {
        if (node.Text == nodeText)
        {
            return node;
        }
    }
    return null;
}

And pass it whatever collection you want to search:

return SearchNodes(nodetext, node.Nodes);

return SearchNodes(nodetext, trv.Nodes);

Also, you can reduce the SearchNodes method to a single line using LINQ:

private TreeNode SearchNodes(string nodeText, TreeNodesCollection nodes)
{
    return nodes.Cast<TreeNode>().FirstOrDefault(n => n.Text == nodeText);
}

Upvotes: 2

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