在WPF列表框C＃中搜索字符串并选择行

Question

in windows form application i do this to find string and select line

            listBoxGCode.SelectedItems.Clear();
            int index = listBoxGCode.FindString(N + e.Value.ToString());              
            if (index != -1)
            {
                listBoxGCode.SetSelected(index, true);

            }

in WPF i cannot get it to work, I've tried this

int index = listBoxGCode.Items.IndexOf((from ListBoxItem a in listBoxGCode.Items where a.Content.ToString() == "N100" select a).First());

when i run this code i get this message Window

unable to cast object of "system.string" to type "system.windows.controls.listboxitem"

do i need to add any code to the .xaml code?

Answer 1

You might have directly added strings into the Items collections of the ListBox , so the type of each item in this expression is actually string, instead of ListBoxItem , this is why you get the InvalidCastException .

from ListBoxItem a in listBoxGCode.Items

To fix this, wrap each string into a ListBoxItem in XAML.

<ListBox x:Name="listBoxGCode">
    <ListBox.Items>
        <ListBoxItem>a</ListBoxItem>
        <ListBoxItem>b</ListBoxItem>
        <ListBoxItem>c</ListBoxItem>
    </ListBox.Items>
</ListBox>

If you want to do this in code behind, you can do it like this

listBoxGCode.Items.Add(new ListBoxItem() { Content = "a" });
listBoxGCode.Items.Add(new ListBoxItem() { Content = "b" });
listBoxGCode.Items.Add(new ListBoxItem() { Content = "c" });