Question

I’m trying to write a simple routine to process a list of items in a ListView and be able to handle all the items or the selected ones only. I expected this to work:

private void PurgeListOfStudies(ListView.ListViewItemCollection lvic)
{
    /// process items in the list...
}

and then call it like this:

PurgeListOfStudies(myStudiesPageCurrent.ListView.Items);

or this

PurgeListOfStudies(myStudiesPageCurrent.ListView.SelectedItems);

However, the two lists have different and unrelated types, ListViewItemCollection and SelectedListViewItemCollection respectively.

I’ve tried changing the type of the parameter to object, ICollection<ListViewItem> and several other things. But since the types seem to be completely unrelated everything fails either at compile time or at runtime during a cast.

This all seems odd to me since these are obviously the same type in reality (a list of ListViewItems).

Am I missing something here?

Answer 1

Use the MSDN documentation.

• ListViewItemCollection
• SelectedListViewItemCollection

As you can see, both classes implement the interfaces: IList, ICollection, and IEnumerable. You should be able to use any of those as a common interface.

Note these are not the Generic versions (i.e. IEnumerable<T>)). You’ll have to enumerate over the collection and manually cast them to your desired object type.

private void PurgeListOfStudies(IEnumerable items)
{
    foreach(MyType currentItem in items) //implicit casting to desired type
    {
        // process current item in the list...
    }
}