WPF Treeview delete operation [duplicate]

This question already has answers here: What is an IndexOutOfRangeException / ArgumentOutOfRangeException and how do I fix it? (5 answers) Closed 1 year ago.

I am working on WPF TreeViews. I am able to add the new Items under tree, but I am not able to delete them from the list. In my code I am trying to get the index of the selected tree item and trying to Remove it. But the code is returning Index "-1". This results in an ArgumentOutOfRangeException.

Please help to fix this.

<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 ge开发者_运维知识库tting exception. What should be the code here ??**             
        }
    }
}

---

below line is having the problem

treeView1.Items.IndexOf(treeView1.SelectedItem))

Since treeview1 is only having one node 'Parent' , rest of the node which you have added is in the node called 'Parent'.

So if you trying to get the index for a node in treeView1.Items it will return -1 except for the node called 'Parent' for which it will return 0.

so you nned to modify the code for removing a node as below.

 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);
              } 

        }     

---

I am not familiar with WPF but in WinForms your approach will cause errors. The first one could be a result of the internal numeration of items. It is like this: 0 -0 -1 -2 1 -0 -0 -1 -1 ...

Another stumbling stone is that IndexOf returns -1 (as you mentioned) if the item was not found. You have to check if the value is -1 first, then navigate to the correct Sublist in Treeview.Nodes.Nodes... and finally call RemoveAt().

I Hope this was helpful Patrick

---

Here's my two cents worth. This code is working on my machine.

    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);
    }

---

  <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);
            }
        }