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？