我很迷茫的一个问题

Question

 private void buildTree(TreeView tv, string kind)
    {
        tv.Nodes.Clear();
        string sql = "";
        switch (kind)
        {
            case "t_RepairItemDetail":
                 sql = "select isNull(ItemIDParentID,'') as ItemIDParentID,ItemID,ItemName,ItemStandHours from t_RepairItemDetail where 1=1 order by ItemID";
                break;
        }


        DataTable dt = DBHelp.ReturnDataTable(sql, kind);
        TreeNode tempNode = null;
        TreeNode tempNodeFirst = null;
        string strItemID= "";
        string strItemName = "";
        string strItemIDParentID = "";


        tempNodeFirst = new TreeNode();
        tempNodeFirst.Value = "";
        tempNodeFirst.Text = "全部";
        tv.Nodes.Add(tempNodeFirst);
        
        for (int i = 0; i < dt.Rows.Count; i++)
        {

            strItemID = dt.Rows[i]["ItemID"].ToString();
            strItemName = dt.Rows[i]["ItemName"].ToString();
            strItemIDParentID= dt.Rows[i]["ItemIDParentID"].ToString();
            if (strItemIDParentID == "")
            {
                tempNode = new TreeNode();
                tempNode.Value = strItemID;
                tempNode.Text = strItemID + ":" + strItemName;
                tempNodeFirst.ChildNodes.Add(tempNode);
            }
            else
            {
                while ( strItemID.Substring(0, ( strItemID.Length <= tempNode.Value.Length ?  strItemID.Length : tempNode.Value.Length)) != strItemIDParentID)
                {
                    if (tempNode.Parent != null)
                    {
                        tempNode = ((TreeNode)tempNode.Parent);
                    }
                    else
                    {
                        tempNode = new TreeNode();
                        tempNode.Value = strItemID;
                        tempNode.Text = strItemID + ":" + strItemName;
                        tempNodeFirst.ChildNodes.Add(tempNode);
                        break;
                    }
                    strItemIDParentID = tempNode.Value;
                }

                TreeNode node1 = new TreeNode();
                node1.Value = strItemID;
                node1.Text = strItemID + ":" + strItemName;
                tempNode.ChildNodes.Add(node1);
                tempNode = node1;
            }
        }
        tv.ExpandDepth = 3;
    }

有谁能告诉我这段代代码中的这句话中的： while ( strItemID.Substring(0, ( strItemID.Length <= tempNode.Value.Length ?  strItemID.Length : tempNode.Value.Length)) != strItemIDParentID)

tempNode的值是从哪里来的？我这里写的是一个TreeView控件的绑定

Answer 1

if (strItemIDParentID == "") { tempNode = new TreeNode(); tempNode.Value = strItemID; tempNode.Text = strItemID + ":" + strItemName; tempNodeFirst.ChildNodes.Add(tempNode); } 在这里实例化的，如果第一次循环不满足strItemIDParentID == ""，那么你的程序应该就要抛异常了

Answer 2

上面的if代码块里不是有么

Answer 3

tempNode = new TreeNode();tempNode.Value = strItemID; 你不是在if里面做的处理吗？