ListViewGroupCollection methods throw new InvalidOperationException
Previously, an InvalidOperationException was thrown if ListViewGroupCollection methods were invoked on a ListView in virtual mode and the Handle had already been created. Starting in .NET 6, these ListViewGroupCollection methods now only check if the ListView is in virtual mode. If it is, they throw an InvalidOperationException with a more descriptive message.
Previous behavior
Consider the following code that adds a ListViewGroup to a ListView:
ListViewGroup group1 = new ListViewGroup
{
Header = "CollapsibleGroup1",
CollapsedState = ListViewGroupCollapsedState.Expanded
};
listView.Groups.Add(group1);
This code produced an InvalidOperationException with the following message:
When the ListView is in virtual mode, you cannot enumerate through the ListView items collection using an enumerator or call GetEnumerator. Use the ListView items indexer instead and access an item by index value.
New behavior
The same code from the Previous behavior section produces an InvalidOperationException with the following message:
You cannot add groups to the ListView groups collection when the ListView is in virtual mode.
Change category
This change affects binary compatibility.
Reason for change
The new InvalidOperationException message is more understandable. In addition, it closes a workaround where the developer could add a ListViewGroup to the ListView before the Handle was created.
Version introduced
.NET 6 RC 2
Recommended action
- Review and, if necessary, update your code so that it doesn't add a ListViewGroup to a ListView in virtual mode.
- If your code handles InvalidOperationException exceptions, you may need to update the message to reflect that the ListView is in virtual mode.
