Question

我正在研究WPF TreeView。我可以在树下添加新项目，但我无法从列表中删除它们。在我的代码中，我试图获取所选树项的索引并尝试删除它。但代码返回索引“-1”。这会产生ArgumentOutOfRangeException。

请帮忙解决这个问题。

<Window x:Class="MyTreeStructure.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Button Content="ADD" Height="23" HorizontalAlignment="Left" Margin="211,50,0,0"
                Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" />
        <TreeView Height="200" HorizontalAlignment="Left" Margin="27,12,0,0" Name="treeView1"
                  VerticalAlignment="Top" Width="120" >
            <TreeViewItem Name="Parent" Header="My Tree Content">
            </TreeViewItem>
        </TreeView>
        <TextBox Height="23" HorizontalAlignment="Left" Margin="211,12,0,0" Name="textBox1"
                 VerticalAlignment="Top" Width="120" />
        <Button Content="Delete" Height="23" HorizontalAlignment="Left" Margin="211,79,0,0"
                Name="button2" VerticalAlignment="Top" Width="75" Click="button2_Click" />
    </Grid>
</Window>

namespace MyTreeStructure
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        private void button1_Click(object sender, RoutedEventArgs e)
        {
            TreeViewItem temp = new TreeViewItem();
            temp.Header = textBox1.Text;
            Parent.Items.Add(temp);
        }

        private void button2_Click(object sender, RoutedEventArgs e)
        {
            textBox1.Text = treeView1.SelectedItem.ToString();
            Parent.Items.RemoveAt(treeView1.Items.IndexOf(treeView1.SelectedItem));        
            **// Here I am getting exception. What should be the code here ??**             
        }
    }
}

Answer 1

下面的

有问题

treeView1.Items.IndexOf(treeView1.SelectedItem))

由于treeview1只有一个节点“Parent”，因此您添加的节点的其余部分位于名为“Parent”的节点中。

因此，如果您尝试获取treeView1.Items中节点的索引，它将返回-1，除了名为“Parent”的节点，它将返回0。

所以你修改了删除节点的代码，如下所示。

 private void button2_Click(object sender, RoutedEventArgs e)     
        {     
            textBox1.Text = treeView1.SelectedItem.ToString();   
            int index = treeView1.Items.IndexOf(treeView1.SelectedItem));   
             if(index < 0)
               {
                   index  = Parent.Items.IndexOf(treeView1.SelectedItem));
               }    

            if(index > 0)
              {
                   Parent.Items.RemoveAt(index);
              } 

        }

Answer 2

我不熟悉WPF，但在WinForms中，您的方法会导致错误。第一个可能是项目内部计算的结果。它是这样的： 0 -0 -1 -2 1 -0 -0 -1 -1 ......

另一个绊脚石是，如果找不到该项，IndexOf将返回-1（如您所述）。您必须先检查值是否为-1，然后导航到Treeview.Nodes.Nodes中的正确子列表...最后调用RemoveAt（）。

我希望这很有帮助帕特里克

Answer 3

为什么不使用Parent.Items.Remove(treeView1.SelectedItem)？

Answer 4

这是我的两分钱。这段代码正在我的机器上运行。

    TreeViewItem t; 

    private void button2_Click(object sender, RoutedEventArgs e)
    {
       // Delete the node
        Parent.Items.RemoveAt(Parent.Items.IndexOf(t));        
     }

    private void treeView1_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
  {
        // Get the selected node
        t = (TreeViewItem)(((TreeView)e.Source).SelectedItem);
    }

Answer 5

  <Grid>
        <TextBox Height="23" HorizontalAlignment="Left" Margin="8,14,0,0" Name="textBox1" VerticalAlignment="Top" Width="127" />
        <Button Height="23" Margin="140,14,0,0" Name="button1" VerticalAlignment="Top" HorizontalAlignment="Left" Width="76" Click="button1_Click">Add Item</Button>

        <Button Height="23" Margin="226,14,124,0" Name="DeleteButton" VerticalAlignment="Top" Click="DeleteButton_Click">Delete Item</Button>
        <TreeView  Margin="10,100,0,13" Name="TreeView1" HorizontalAlignment="Left" VerticalAlignment="Top" Width="194" Height="200">
            <TreeViewItem x:Name="Parent" Header="Cold Drinks">
                <TreeViewItem Header="Coke"></TreeViewItem>
                <TreeViewItem Header="Pepsi"></TreeViewItem>
                <TreeViewItem Header="Orange Juice"></TreeViewItem>
                <TreeViewItem Header="Milk"></TreeViewItem>
                <TreeViewItem Header="Iced Tea"></TreeViewItem>
                <TreeViewItem Header="Mango Shake"></TreeViewItem>
            </TreeViewItem>
        </TreeView>
    </Grid>






        private void button1_Click(object sender, RoutedEventArgs e)
        {
            TreeViewItem newChild = new TreeViewItem();
            newChild.Header = textBox1.Text;
            Parent.Items.Add(newChild);
        }
        private void DeleteButton_Click(object sender, RoutedEventArgs e)
        {

            int index = TreeView1.Items.IndexOf(TreeView1.SelectedItem);
            if (index < 0)
            {
                index = Parent.Items.IndexOf(TreeView1.SelectedItem);
            }

            if (index >= 0 && ((System.Windows.Controls.TreeViewItem)TreeView1.SelectedItem).Name.Contains("Parent"))
            {                
                TreeView1.Items.RemoveAt(index);
            }
            else if (index >= 0)
            {
                Parent.Items.RemoveAt(index);
            }
        }

WPF Treeview删除操作

5 个答案: