Sort TreeView Automatically Upon Adding Nodes

Question

Is there an easy way to add nodes to a WinForms .NET TreeView control where the new nodes being added are inserted at the correct index so the entire list of nodes is sorted alphabetically? Pretty much having the same result as TreeView.Sort().

I have a TreeView that continually grows to a couple hundred nodes. The user can view this TreeView in real time as it grows. I'd prefer to just insert the nodes at the correct index, rather than calling TreeView.Sort() each time after a node is added.

Can this be done?

Answer 1

In winforms, you can simply set the TreeView's .Sorted property to True.

When Sorted is set to true, the TreeNode objects are sorted in alphabetical order by their Text property values. You should always use BeginUpdate and EndUpdate to maintain performance when adding a large quantity of items to a sorted TreeView. When the text of an existing node is changed, you must call Sort to resort the items.

Ref MSDN

Answer 2

Why don't you create new classes that inherits from TreeView and TreeNodeCollection? The new TreeView will use your new TreeNodeCollection and you can override the Add() method of the TreeNodeCollection to do what you're suggesting.

The method would have to: 1. Find the correct position to insert into and 2. Insert the new node.

The most trivial implementation would iterate through the collection until thisNode.value<=newNode.value<nextNode.value. Then insert before nextNode.Index. You could see a performance increase if you use a different search algorithm, depending on the size of the collection. (Something like a binary search comes to mind.)

Note: You could also just create an extension method on a TreeNodeCollection that does the same thing. However, overriding the Add() method ensures your TreeView is always sorted. Creating only an extension method may lead to undefined results if it is not already sorted before your AddIntoSorted() call.