WP8 Item not found in LongListSelector

Question

I am trying to scroll to a particular item in LongListSelector, but my longlistselector cannot find it and crashes when I call the llsTest.ScrollTo(m) function.

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C#:

public class MyItem 
{
    public string s1 {get;set;}
    public string z1 {get;set;}

}

List<MyItem> list= new List<MyItem>();
list.Add(new MyItem() { s1 = "First", z1 = "Second" });
list.Add(new MyItem() { s1 = "Third", z1 = "Fourth" });
list.Add(new MyItem() { s1 = "Fifth", z1 = "Sixth" });
list.Add(new MyItem() { s1 = "Sek8", z1 = "kj98" });
list.Add(new MyItem() { s1 = "lkdsj9", z1 = "lkdjo0" });
list.Add(new MyItem() { s1 = "jkdlhf", z1 = "98uifie" });
list.Add(new MyItem() { s1 = "Seventh11", z1 = "Eighth32" });
list.Add(new MyItem() { s1 = "Seventh45", z1 = "Eighth67" });
list.Add(new MyItem() { s1 = "Seventh86", z1 = "Eighth89" });
list.Add(new MyItem() { s1 = "Seventh6", z1 = "Eighth7" });
list.Add(new MyItem() { s1 = "Sevent4h", z1 = "Eighth8" });
list.Add(new MyItem() { s1 = "Seventh7i", z1 = "Eighthlp" });
list.Add(new MyItem() { s1 = "Seventh-09", z1 = "Eighth-0" });
list.Add(new MyItem() { s1 = "Seventh1q", z1 = "Eighthh65" });
list.Add(new MyItem() { s1 = "Second Last", z1 = "Last" });

MyItem m = new MyItem() { s1 = "Second Last", z1 = "Last" };

llsTest.ItemsSource = list;
llsTest.ScrollTo(m);  // **<========Crashes here, m cannot be found!**

---

Here is the XAML:

<phone:LongListSelector Name="llsTest">
    <phone:LongListSelector.ItemTemplate>
        <DataTemplate>
            <TextBlock>
                <Run Text="{Binding s1}"/><LineBreak/>
                <Run Text="{Binding z1}"/>
            </TextBlock>
        </DataTemplate>
    </phone:LongListSelector.ItemTemplate>
 </phone:LongListSelector>

Answer 1

MyItem m = new MyItem() { s1 = "Second Last", z1 = "Last" }; now after this above line m is never added to list. so obviously it will throw an exception while trying to scroll to a non existing item.

Note that, every call to new creates a new object, so even if the content of objects are same, different objects would never be the same.

so object passed in to

list.Add(new MyItem() { s1 = "Second Last", z1 = "Last" }); 

isn't same as object created afterwards.

MyItem m = new MyItem() { s1 = "Second Last", z1 = "Last" };

u need to call list.Add(m) before call to llsTest.ScrollTo(m);

u can then remove a redundant element by removing line list.Add(new MyItem() { s1 = "Second Last", z1 = "Last" });

Answer 2

Instead of passing a new item to ScrollTo, give the item from the list array. I see from the code that you want to scroll to the 15th item. So write the code like below:

llsTest.ScrollTo(list[15]);