System.Collections.SortedList.IndexOfKey C# (CSharp) Method

        public virtual int IndexOfKey(Object key)
        {
            if (key == null)
                throw new ArgumentNullException(nameof(key), SR.ArgumentNull_Key);
            Contract.EndContractBlock();
            int ret = Array.BinarySearch(_keys, 0, _size, key, _comparer);
            return ret >= 0 ? ret : -1;
        }

        public void LoadMoudelTree(string roleCode)
        {
            DataTable tempTable = roleBll.GetUserModuleListByRoleCode(roleCode);
            this.UltraWebTreeModule.Nodes.Clear();
            SortedList allTreeNodes = new SortedList();
            foreach (DataRow row in tempTable.Rows)
            {
                Node newNode = base.CreateNode(Convert.ToString(row["modulecode"]), FunctionText.ResourceManager.GetString(row["LANGUAGE_KEY"].ToString()) + this.CreateFunctionList(Convert.ToString(row["FunctionList"]), Convert.ToString(row["FunctionListed"]), Convert.ToString(row["Authorized"])), Convert.ToString(row["authorized"]).Equals("Y"), Convert.ToDecimal(tempTable.Compute("count(modulecode)", "parentmodulecode='" + row["modulecode"] + "'")) == 0M);
                allTreeNodes.Add(Convert.ToString(row["modulecode"]), newNode);
                if (row["parentmodulecode"].ToString().Trim().Length > 0)
                {
                    if (allTreeNodes.IndexOfKey(row["parentmodulecode"]) >= 0)
                    {
                        ((Node)allTreeNodes.GetByIndex(allTreeNodes.IndexOfKey(row["parentmodulecode"]))).Nodes.Add((Node)allTreeNodes.GetByIndex(allTreeNodes.IndexOfKey(row["modulecode"])));
                    }
                }
                else
                {
                    this.UltraWebTreeModule.Nodes.Add((Node)allTreeNodes.GetByIndex(allTreeNodes.IndexOfKey(Convert.ToString(row["modulecode"]))));
                }
                foreach (Node node in this.UltraWebTreeModule.Nodes)
                {
                    node.Expand(true);

                }
            }
        }