C# 将列表值从Windows窗体类返回到另一个类 我相信这非常简单，但遗憾的是，我也是。这是我的课程：

我正试图填满一个树状视图，但那是一整套完全不同的问题。非常感谢您的帮助。多谢各位

试试下面。我用记事本编辑代码，所以请原谅任何语法错误

public void fillTreeViewByList()
{
    connect.Open();

    TreeViewColorDescNodes firstNode = new TreeViewColorDescNodes();  // Everything from here down is probably wrong...

    tvDiscountMaintenance.Nodes.Add("Select All"); 

    //firstNode has the instance of TreeViewColorDescNodes() which has list of items from DB
    //So you need to iterate the items from this instance
    foreach (string item in firstNode.ColDescNode)
    {
        //You need to create the tree node with text in item rather than List name
        TreeNode colorDesc = new TreeNode(item);

        //You need to add the tree node to the tree control rather than the string
        tvDiscountMaintenance.Nodes[0].Nodes.Add(colorDesc);
    }
}

---

请描述期望的结果以及哪里出了问题。此外，您的类似乎缺少

class

语句。您正在创建

TreeViewColorDescNodes

的新实例，但从未访问它。您是否打算使用例如：

firstNode.ColDescNode

而不仅仅是

ColDescNode

？我可以在类TreeViewCodesDescNodes中运行存储过程，但是当我用以下命令在表单中实例化该类时：TreeViewColorDescNodes firstNode=new TreeViewColorDescNodes（）；firstNode.ColDescNode仍然为空。计数=0。我改变了我的表单代码，以符合Mukul Varshney的建议，这似乎是有道理的，但我仍然有同样的问题。请解释“课堂似乎缺少一个‘课堂’陈述”。也许这就是问题所在。谢谢你的帮助。如果我将列表和存储过程移动到表单方法fillTreeViewByList中，那么经过您所做的代码更正，它就可以工作了。但是，如果我尝试将列表从类TreeViewColorDescNodes返回到表单方法fillTreeViewByList，则firstNode仍然为空。计数=0。我几乎放弃了。再次感谢您的帮助。除了在TreeViewColorDescNodes类中，您是否有任何ColDescNode声明？在tvDiscountMaintenance.Nodes.Add（“全选”）处也放置一个断点；看看firstNode.ColDescNode列表的计数是多少？

public void fillTreeViewByList()
{
    connect.Open();

    TreeViewColorDescNodes firstNode = new TreeViewColorDescNodes();  // Everything from here down is probably wrong...

    tvDiscountMaintenance.Nodes.Add("Select All"); 
    foreach (var item in ColDescNode)
    {
        TreeNode colorDesc = new TreeNode(ColDescNode.ToString());
        tvDiscountMaintenance.Nodes[0].Nodes.Add(item.ToString());  
    }
}

public void fillTreeViewByList()
{
    connect.Open();

    TreeViewColorDescNodes firstNode = new TreeViewColorDescNodes();  // Everything from here down is probably wrong...

    tvDiscountMaintenance.Nodes.Add("Select All"); 

    //firstNode has the instance of TreeViewColorDescNodes() which has list of items from DB
    //So you need to iterate the items from this instance
    foreach (string item in firstNode.ColDescNode)
    {
        //You need to create the tree node with text in item rather than List name
        TreeNode colorDesc = new TreeNode(item);

        //You need to add the tree node to the tree control rather than the string
        tvDiscountMaintenance.Nodes[0].Nodes.Add(colorDesc);
    }
}