System.Exception {System.ArgumentException} Value does not fall within the expected range

问题

I'm getting this exception whenever i try to access m list picker control in my app.

+       this    {App_name.App}  App_name.App
+       sender  {App_name.App}  object {App_name.App}
-       e   {System.Windows.ApplicationUnhandledExceptionEventArgs} System.Windows.ApplicationUnhandledExceptionEventArgs
+       base    {System.Windows.ApplicationUnhandledExceptionEventArgs} System.EventArgs {System.Windows.ApplicationUnhandledExceptionEventArgs}
+       ExceptionObject {System.ArgumentException: Value does not fall within the expected range.}  System.Exception {System.ArgumentException}
        Handled false   bool
+       Non-Public members

Code for my list picker is

<ListBox Margin="0,417,0,0">
            <ListBoxItem>
                <toolkit:ListPicker Name="LearnerFileChooser" Width="431" >
                    <toolkit:ListPickerItem Content="A" />
                    <toolkit:ListPickerItem Content="B" />
                    <toolkit:ListPickerItem Content="C" />
                    <toolkit:ListPickerItem Content="E" />
                    <toolkit:ListPickerItem Content="F" />
                    <toolkit:ListPickerItem Content="G" />
                    <toolkit:ListPickerItem Content="H" />
                </toolkit:ListPicker>
            </ListBoxItem>

If i reduce the no. of items to 4 then it works properly but it crashes on more then 4 items.

I'm trying to create a list of alphabets from which user can choose.

回答1:

It's a known issue.

You must bind the items to be able to use more than 5.

Explanation on Codeplex:

ListPicker as an ItemsControl, gets its Items property set to a list of ListPickerItems in your example. ListPickerItems are UIElements, and the ListPicker renders them in its presenter. When there are 5 or less items, the expanded mode opens on the current page, and you can see all the items in the presenter.

But when 6 or more items are present, opening the list picker goes to full mode which opens a new page. This new page has a listbox, which gets its items property set to the listpicker's items. This is where it breaks. By setting the listbox's items to the listpicker's items (in this case a list of listpickeritems), the listbox will put those UIElements into its view. Now a single listboxitem is included in two places on the visual tree.

Because of this issue, ListPicker only supports databinding and templating. DO NOT set the ListPicker's items to specific UIElements.

来源：https://stackoverflow.com/questions/22119053/system-exception-system-argumentexception-value-does-not-fall-within-the-expec

标签

windows-phone-8

toolkit

listpicker