I need this code in my app:

    balls.addAll(new Ball[]{}); // Invalidate

...in a scenario where I have changed the properties of individual objects inside the 'balls' ObservableList; but I didn't add or remove elements from the list so it didn't have structural changes. But I have a ListChangeListener that needs to react to any kind of change inside balls.

I'm being forced to use the addAll() method, which always triggers the invalidation event, passing an empty array so no actual change happens. This is a fragile solution, the collection could be optimize to not send that event in this case, so I'd have to resort to a less efficient solution like setAll(balls.toArray()).

I could also keep a reference to the ListChangeListener object, and just invoke it directly. But this requires keeping an extra field somewhere, and also allocating a dummy ListChangeListener.Change object.

Some ideas:

1) Have a public method in ObservableList, e.g. invalidate(begin, end).
2) Have a method to return the collection's listeners. This would avoid the need to keep track of my listener, but the resulting code in ball's update site would be even more complex because I'd need to handle a collection of listeners, looping and calling each.

This is clearly just a nice-to-have, as I have workarounds and they're not too bad... but I think the suggested invalidated API would be semantically significant, as a mechanism to explicitly support non-structural update notifications.