Sorting child nodes of a treeview after populating the treeview in c# winforms

Question

I am having trouble sorting child nodes of a treeview in my winforms program. My treeview is populated by some XML files and it uses an internal text inside the xml files as

Answer 1

I've written some custom comparers to make creating the comparer you need here somewhat easier to do: MultiComparer and ProjectionComparer. Together, you could create a comparer to sort what you need on the fly without having to create a class by hand. What I provide here isn't actually how I have the classes written, I trimmed off a lot of code for brevity (though left some helpers to be easier to use).

To create the comparer:

var comparer = OrderedComparer.Create(
    ProjectionComparer.Create((TreeNode tn) => tn.Text.Substring(0, 1)),
    ProjectionComparer.Create((TreeNode tn) => Convert.ToInt32(tn.Text.Substring(1)))
);
treeView.TreeViewNodeSorter = comparer;

And the classes:

public static class OrderedComparer
{
    public static OrderedComparer<TSource> Create<TSource>(params IComparer<TSource>[] comparers)
    { return new OrderedComparer<TSource>(comparers); }
}
public static class ProjectionComparer
{
    public static ProjectionComparer<TSource, TKey> Create<TSource, TKey>(Func<TSource, TKey> keySelector)
    { return new ProjectionComparer<TSource, TKey>(keySelector); }
}
public sealed class OrderedComparer<TSource> : Comparer<TSource>
{
    public OrderedComparer(params IComparer<TSource>[] comparers)
    {
        this.comparers = comparers.ToArray();
    }
    private IComparer<TSource>[] comparers;

    public override int Compare(TSource x, TSource y)
    {
        var cmp = 0;
        foreach (var comparer in comparers)
            if ((cmp = comparer.Compare(x, y)) != 0)
                break;
        return cmp;
    }
}
public sealed class ProjectionComparer<TSource, TKey> : Comparer<TSource>
{
    public ProjectionComparer(Func<TSource, TKey> keySelector)
    {
        this.keySelector = keySelector;
        this.keyComparer = Comparer<TKey>.Default;
    }
    private Func<TSource, TKey> keySelector;
    private IComparer<TKey> keyComparer;

    public override int Compare(TSource x, TSource y)
    {
        var xKey = keySelector(x);
        var yKey = keySelector(y);
        return keyComparer.Compare(xKey, yKey);
    }
}

Answer 2

You're using alphabetic sorting, so D10 comes after D1.
You should try to sort discarding "D" char and converting the rest of string to a number.

Answer 3

Following is the solution I have used in my current project.

public class NodeSorter : IComparer
{
   public int Compare(object x, object y)
   {
      TreeNode tx = x as TreeNode;
      TreeNode ty = y as TreeNode;
      if (tx.Name== null || ty.Name== null)
         return 0;
      return (-1) * string.Compare(tx.Name.ToString(), ty.Name.ToString());
   }
} 

tvListofItems.TreeViewNodeSorter = new NodeSorter();
tvListofItems.Sort();              

Answer 4

You need to create a custom comparer and assign it to the TreeViewNodeSorter property:

public class NodeSorter : System.Collections.IComparer
{
    public int Compare(object x, object y)
    {
        TreeNode tx = (TreeNode)x;
        TreeNode ty = (TreeNode)y;

        // Your sorting logic here... return -1 if tx < ty, 1 if tx > ty, 0 otherwise
        ...
    }
}


...

treeView.TreeViewNodeSorter = new NodeSorter();
treeView.Sort();