Difference between ObservableCollection and BindingList
Solution 1:
An ObservableCollection
can be updated from UI exactly like any collection. The true difference is rather straightforward:
ObservableCollection<T>
implements INotifyCollectionChanged
which provides notification when the collection is changed (you guessed ^^)
It allows the binding engine to update the UI when the ObservableCollection
is updated.
However, BindingList<T>
implements IBindingList
.
IBindingList
provides notification on collection changes, but not only that. It provides a whole bunch of functionality which can be used by the UI to provide a lot more things than only UI updates according to changes, like:
- Sorting
- Searching
- Add through factory (AddNew member function).
- Readonly list (CanEdit property)
All these functionalities are not available in ObservableCollection<T>
Another difference is that BindingList
relays item change notifications when its items implement INotifyPropertyChanged
. If an item raises a PropertyChanged
event, the BindingList
will receive it an raises a ListChangedEvent
with ListChangedType.ItemChanged
and OldIndex=NewIndex
(if an item was replaced, OldIndex=-1
). ObservableCollection
doesn't relay item notifications.
Note that in Silverlight, BindingList
is not available as an option: You can however use ObservableCollection
s and ICollectionView
(and IPagedCollectionView
if I remember well).
Solution 2:
The practical difference is that BindingList is for WinForms, and ObservableCollection is for WPF.
From a WPF perspective, BindingList isnt properly supported, and you would never really use it in a WPF project unless you really had to.
Solution 3:
The most important differences such as features and change notifications about the contained elements are already mentioned by the accepted answer but there are more, which also worth mentioning:
Performance
When AddNew
is called, BindingList<T>
searches for the added item by an IndexOf
lookup. And if T
implements INotifyPropertyChanged
the index of a changed element is also searched by IndexOf
(though there is no new lookup as long as the same item changes repeatedly). If you store thousands of elements in the collection, then ObservableCollection<T>
(or a custom IBindingList
implementation with O(1) lookup cost) can be more preferable.
Completeness
The
IBindingList
interface is a huge one (maybe not the cleanest design) and allows the implementors to implement only a subset of its features. For example, theAllowNew
,SupportsSorting
andSupportsSearching
properties tell whetherAddNew
,ApplySort
andFind
methods can be used, respectively. It often surprises people thatBindingList<T>
itself does not support sorting. Actually it provides some virtual methods letting the derived classes add the missing features. TheDataView
class is an example for a fullIBindingList
implementation; however, it is not for typed collections in the first place. And theBindingSource
class in WinForms is a hybrid example: it supports sorting if it wraps anotherIBindingList
implementation, which supports sorting.ObservableCollection<T>
is already a complete implementation of theINotifyCollectionChanged
interface (which has only a single event). It also has virtual members butObservableCollection<T>
is typically derived for the same reason as its baseCollection<T>
class: for customizing add/remove items (eg. in a data model collection) rather than adjusting binding features.
Copy vs. wrapping
Both ObservableCollection<T>
and BindingList<T>
have a constructor, which accepts an already existing list. Though they behave differently when they are instantiated by another collection:
-
BindingList<T>
acts as an observable wrapper for the provided list, and the changes performed on theBindingList<T>
will be reflected on the underlying collection as well. -
ObservableCollection<T>
on the other hand passes a newList<T>
instance to the baseCollection<T>
constructor and copies the elements of the original collection into this new list. Of course, ifT
is a reference type changes on the elements will be visible from the original collection but the collection itself will not be updated.