Find selected WPF Listbox entries

Question

I've been trying iterate through the selected items of a listbox in WPF, with the following code;

        try
        {
            for (int i = 0; i < mylistbox.SelectedItems.Count; i++)
            {
                ListItem li = (ListItem)mylistbox.SelectedItems[i];

                string listitemcontents_str = li.ToString();
            }
        }
        catch(Exception e)
        {
            // Error appears here
            string error = e.ToString();
        }

However I receive an invalid cast exception;

System.InvalidCastException: Unable to cast object of type 'mylist' to type 'System.Windows.Documents.ListItem'.

Is there a way around this?

score 5 · Answer 1 · edited May 23 '17 at 12:30

5

I prefer to do it using data binding: Sync SelectedItems in a muliselect listbox with a collection in ViewModel

edited May 23 '17 at 12:30

Community

1
1

answered May 06 '10 at 13:20

Brian Genisio

47,787
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I agree with Brian. This would be a better approach if you want to get the power of WPF. – Mark Pearl May 06 '10 at 13:42

score 4 · Answer 2 · answered May 06 '10 at 13:24

4

  for (int i = 0; i < mylistbox.SelectedItems.Count; i++)
    {
        List**Box**Item li = (List**Box**Item)mylistbox.SelectedItems[i];

        string listitemcontents_str = li.ToString();
    }

answered May 06 '10 at 13:24

score 0 · Answer 3 · answered May 06 '10 at 13:17

0

This should work:

       for (int i = 0; i < mylistbox.SelectedItems.Count; i++)
        {
            var li = mylistbox.SelectedItems[i];

            string listitemcontents_str = li.ToString();
        }

answered May 06 '10 at 13:17

Scrappydog

2,864
1
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score 0 · Accepted Answer · answered May 12 '10 at 16:06

A way I found was to assign the listbox onto an object then cast this onto a DataRowView. Seems to work and I can get access to the fields inside, by their respective column names.

object selected = mylistbox.SelectedItem; DataRow row = ((DataRowView)selected).Row;
string thecontents = row["columnname"].ToString().TrimEnd();

score 0 · Answer 5 · answered May 12 '10 at 19:21

You are confusing ListItem with ListBoxItem.

If you do nothing special, a ListBox will create ListBoxItem containers for the data you bind to it. ListItem is used inside FlowDocument and is basically a numbered or bulleted point in a document.

That said, data binding would be better. If you were using data binding, SelectedItems would not be a ListBoxItem but would be your actual data item that was bound. You can cast this to the appropriate type and use it.

Indigo Praveen · Answer 6 · 2010-05-06T13:39:52.247

The listbox adds it's items as a collection of objects, so it can't cast it to ListItem. So for your purpose , you can do as following :

for (int i = 0; i < mylistbox.SelectedItems.Count; i++) 
        {           

            string listitemcontents_str = mylistbox.SelectedItems[i].ToString(); 
        }

If you really want to use ListBoxItem , please add these items to your listbox e.g.

ListBoxItem li = new ListBoxItem();
li.Content = "Hello";
mylistbox.Items.Add(li);

then you can do what you want without Invalid cast exception:

for (int i = 0; i < mylistbox.SelectedItems.Count; i++)
            {
            ListBoxItem li = (ListBoxItem)mylistbox.SelectedItems[i];
            string s = li.ToString();
            }

Not true. Unless GetContainerForItemOverride is overridden, a ListBoxItem will be generated as a wrapper for every object (unless the object itself is a ListBoxItem). — , May 06 '10 at 13:42

Find selected WPF Listbox entries

6 Answers6

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