检查 TreeView 中选中的节点数

我是使用树视图的新手，我希望能够确保树视图只能检查一个子节点，如果有人尝试检查多个子节点，它会停止检查事件并取消选择所有父节点和子节点。我该怎么做呢？到目前为止，这就是我所得到的，但它表现得很奇怪。有什么建议么？

Update:为了澄清一些事情，这是一个 win 表单树视图，父节点是一个类别，每个类别可以包含多个项目。我只希望用户能够一次选择一个类别并从该类别中选择一项。

private void tvRecipes_BeforeCheck(object sender, TreeViewCancelEventArgs e)
{
    int checkedNodeCount = 0;

    if (e.Node.Parent != null && !e.Node.Parent.Checked)
        e.Cancel = true;
    else
    {
        foreach (TreeNode node in tvRecipes.Nodes)
        {
            if (node.Checked)
                ++checkedNodeCount;

            if (checkedNodeCount > 2)
            {
                MessageBox.Show("Only one recipe can be selected at a time, please deselect the current recipe and try again.", "Too Many Recipes Selected", MessageBoxButtons.OK, MessageBoxIcon.Error);

                e.Cancel = true;
            }
        }
    }

经过一番折腾后，我找到了我想要的解决方案。我已将其发布在下面：

private bool CheckNumOfSelectedChildern(TreeViewEventArgs e)
{
    bool Valid = true;
    int selectedChildern = 0;

    foreach (TreeNode node in tvRecipes.Nodes)
    {
        if (node.Checked)
        {
            foreach (TreeNode child in node.Nodes)
            {
                if (child.Checked)
                    ++selectedChildern;
            }
        }
    }

    if (selectedChildern > 1)
    {
        MessageBox.Show("Only one recipe per category can be selected at a time, please deselect the current recipe and try again.", "Too Many Recipes Selected", MessageBoxButtons.OK, MessageBoxIcon.Error);
        e.Node.Checked = false;
        e.Node.Parent.Checked = false;
        Valid = false;
    }       
    return Valid;
}

private bool CheckNumOfSelectedParents(TreeViewEventArgs e)
{
    bool Valid = true;
    int selectedParent = 0;

    foreach (TreeNode root in tvRecipes.Nodes)
    {
        if (root.Checked)
            ++selectedParent;
    }

    if (selectedParent > 1)
    {
        MessageBox.Show("Only one recipe category can be selected at a time, please deselect the current recipe and try again.", "Too Many Recipes Selected", MessageBoxButtons.OK, MessageBoxIcon.Error);
        e.Node.Checked = false;
        Valid = false;
    }
    return Valid;
}

private void tvRecipes_BeforeCheck(object sender, TreeViewCancelEventArgs e)
{
    if (e.Node.Parent != null && !e.Node.Parent.Checked)
        e.Cancel = true;
    else if (e.Node.Checked)
    {
        foreach (TreeNode child in e.Node.Nodes)
        {
            if (child.Checked)
                e.Cancel = true;
        }
    }
}

private void tvRecipes_AfterCheck(object sender, TreeViewEventArgs e)
{
    if (CheckNumOfSelectedParents(e))
    {
        if (e.Node.Parent != null && e.Node.Parent.Checked)
        {
            if (e.Node.Checked)
            {
                if (CheckNumOfSelectedChildern(e))
                {
                    RecipeDs = RetrieveRecipe.FillRecipeDs(e.Node.Text);
                    DataBindControls();
                }                    
            }
            else
            {
                RemoveLabelsFromLayout();
                RemoveDataBindings();
                RecipeDs.Clear();
                this.Refresh();
            }
        }
    }
}

您的 if (checkedNodeCount > 2)... 应该位于 foreach 循环之外。

在 for 循环内，每次都会运行它。我猜这就是你所说的“表现古怪”

也许您应该更详细地说明什么是不正确的行为。