ObservableCollection<> vs. List<>

Question

I have lots of entities with nested List<> in each.

For example, I have BaseEntity which has List<ColumnEntity>. ColumnEntity class has List<Info> and so on.

We are working with a WPF UI, and we need to track all changes in every List of BaseEntity. It is implemented by instantiating a new ObservableCollection based on the needed list, and with binding to that ObservableCollection.

What are the pros and cons changing all these nested Lists to ObservableCollections? So we can track all changes in BaseEntity itself without reassigning each list of BaseEntity to modified bound ObservableCollection?

Assuming that methods specific to List are never used.

Answer 1

Interesting question, considering that both List and ObservableCollection implement IList<T> there isn't much of a difference there, ObservableCollection also implements INotifyCollectionChanged interface, which allows WPF to bind to it.

One of the main differences is that ObservableCollection does not have AddRange method, which might have some implications.

Also, I would not use ObservableCollection for places where I know I would not be binding to, for this reason, it is important to go over your design and make sure that you are taking the correct approach in separating layers of concern.

As far as the differences between Collection<T> and List<T> you can have a look here Generic Lists vs Collection

Answer 2

It depends on exactly what you mean by this:

we need to track all changes in every List of BaseEntity

Would it be enough to track changes to objects already in the list? Or do you need to know when objects are removed from/are added to/change positions within the list?

If a list will contain the same items for their whole lifetime, but the individual objects within that list will change, then it's enough for just the objects to raise change notifications (typically through INotifyPropertyChanged) and List<T> is sufficient. But if the list will contain different objects from time to time, or if the order changes, then you should use ObservableCollection<T>.

So while the differences may be interesting (and a previous poster has already covered those), typically you won't have that much of a choice - either you need ObservableCollection<T> or you don't.