如何有效地从 TreeView 中删除选中的项目?

How to Efficiently Delete Checked Items from a TreeView?(如何有效地从 TreeView 中删除选中的项目?)

问题描述

如何轻松遍历 TreeView 中的所有节点，检查它们的 .Checked 属性，然后删除所有选中的节点?

How can one easily iterate through all nodes in a TreeView, examine their .Checked property and then delete all checked nodes?

这看起来很简单，但您不应该修改您正在迭代的集合，从而消除foreach"循环的可能性.(.Nodes.Remove 调用正在修改集合.)如果尝试这样做，效果是只有大约一半的 .Checked 节点被删除.

It seems straightforward, but you aren't supposed to modify a collection through which you are iterating, eliminating the possibility of a "foreach" loop. (The .Nodes.Remove call is modifying the collection.) If this is attempted, the effect is that only about half of the .Checked nodes are removed.

即使要使用两遍:首先创建一个临时索引列表，然后在第二遍中按索引删除 - 每次删除时索引都会更改，从而使索引列表的完整性无效.

Even if one were to use two passes: first creating a list of temporary indexes, and then removing by index on the second pass -- the indexes would change upon each removal, invaliding the integrity of the index list.

那么，最有效的方法是什么?

So, what is the most efficient way to do this?

这是一个看起来不错的代码示例，但实际上只删除了大约一半的 .Checked 节点.:

Here is an example of code that looks good, but actually only removes about half of the .Checked nodes.:

            foreach (TreeNode parent in treeView.Nodes)
            {
                if (parent.Checked)
                {
                    treeView.Nodes.Remove(parent);
                }
                else
                {
                    foreach (TreeNode child in parent.Nodes)
                    {
                        if (child.Checked) parent.Nodes.Remove(child);
                    }
                }
            }

(是的，目的只是从两层深的树中修剪节点.)

(Yes, the intention is only to prune nodes from a tree that is two levels deep.)

推荐答案

这将在枚举完节点后将其移除，并可递归用于n层节点.

This will remove the nodes after enumerating them, and can be used recursively for n-tiers of nodes.

void RemoveCheckedNodes(TreeNodeCollection nodes)
{
    List<TreeNode> checkedNodes = new List<TreeNode>();

    foreach (TreeNode node in nodes)
    {
        if (node.Checked)
        {
            checkedNodes.Add(node);
        }
        else
        {
            RemoveCheckedNodes(nodes.ChildNodes);
        }
    }

    foreach (TreeNode checkedNode in checkedNodes)
    {
        nodes.Remove(checkedNode);
    }
}

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