Populate TreeView from Simple list

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Introduction

This tip explains a very simple example on how to populate TreeView from some sort of list.

In this example, I used  List<class> as variable, but it can easily be array or something similar.

It is written using Visual C# 2010 Express, but it should be easily adapted to C/C++, VB...

Background

It's becoming ever harder and frustrating to find simplified examples on how to do a simple task: like populate TreeView.

As a hardware engineer, often I have to waste hours to find out how to add two and two. Examples often unnecessary use eighteen layers of abstraction with data coming over SXw satellite link form XttAS database over ISPR4 link ... (you got the idea ) just to show you how to change text in EditBox!

Screenshot

Using the Code

1. Copy-paste the complete source file to a new project
2. Add controls to Form:
• TreeView tvData
• Button btnPopulate
• ListBox lbData containing Items:
• 0 Movies
• 1 Comedy
• 1 SF
• 2 5th Element
• 3 Bruce Willis
• 3 Mila Jovovic
• 2 Matrix
• 0 Music
• 1 Alternative
• 1 R&R
• 2 Coldplay
• 1 Clasic
• 0 Pictures
• 1 Trips
• 2 Europe
• 3 Stuttgart
• 4 Mercedes-Benz museum
• 2 Africa

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;

namespace TreeViewExample
{
   public partial class Form1 : Form
   {
      public class kData {   // instead of class you can use struct, but with some difficulties
         public int index;
         public int level;
         public string NodeText;
         public string OtherData;
         //public stData()  { } // here you can initialize variables
      };
      List<kData> L; // instead of list you can use array, but I prefer Lists

      public Form1() {
         InitializeComponent();
      }

      private void btnPopulate_Click(object sender, EventArgs e) {
         // take data from ListBox and store it to List
         string line;
         L = new List<kData>();
         for (int i = 0; i < lbData.Items.Count; i++)  {
            line = lbData.Items[i].ToString();
            L.Add(new kData());
            L[i].index = i;
            L[i].level = Convert.ToInt32(line.Substring(0,1));
            L[i].NodeText = line.Substring(2);
            L[i].OtherData = "some other data you might need";
         }

         populateBaseNodes();
      }

      public void populateBaseNodes()
      {
         int i;
         tvData.Nodes.Clear();
         tvData.BeginUpdate();

         for (i = 0; i < L.Count(); i++) {
            if (L[i].level == 0) {
               tvData.Nodes.Add(L[i].NodeText, L[i].NodeText);
               tvData.Nodes[tvData.Nodes.Count - 1].Tag = L[i];
            }
         }

         for (i = 0; i < tvData.Nodes.Count; i++)
            populateChilds(tvData.Nodes[i]);

         tvData.EndUpdate();
         tvData.Refresh();
      }

      public void populateChilds(TreeNode parentNode)  
      {
         kData parentRed = (kData)parentNode.Tag;

         for (int i = parentRed.index + 1; i < L.Count; i++) {
            if (L[i].level == (parentRed.level + 1)) {
               parentNode.Nodes.Add(L[i].NodeText, L[i].NodeText);
               parentNode.Nodes[parentNode.Nodes.Count - 1].Tag = L[i];
               populateChilds(parentNode.Nodes[parentNode.Nodes.Count - 1]);
            }
            if (L[i].level <= parentRed.level) break;
         }
      }
   }
} 

Final Note

The code should be self-explanatory.

If it isn't, then I have failed in my attempt and feel free to give it bad marks.