TreeViewitem无法选择= null

Question

I have a problem with the selection of a TreeViewItem in my tree view. My following code returns null when I select an item in my tree view.

What do I do wrong?

TreeViewItem item = e.OriginalSource as TreeViewItem;

Answer 1

As per your latest image, e.OriginalSource is a TreeView . When you cast e.OriginalSource like this:

TreeViewItem item = e.OriginalSource as TreeViewItem;

... item will always be null . This is because your type cast cannot convert e.OriginalSource into your desired type. If you this hard cast instead:

TreeViewItem item = (TreeViewItem)e.OriginalSource;

You would get a CastException that explains you why.

So what you got to do is to cast into the correct type like this:

TreeViewItem tree = e.OriginalSource as TreeView; // I am a tree view :-)

... and then select from tree.Items the item you require.

Answer 2

e.Source and e.OriginalSource refer to the TreeView not the TreeViewItem selected.

Try this to get the selected item:

TreeViewItem item = e.NewValue as TreeViewItem;

Or this to get the previously selected item:

TreeViewItem item = e.OldValue as TreeViewItem;