Implementing INotifyPropertyChanged with ObservableCollection

问题

I want to pull data from a database to display into a ComboBox, and then allow users to select values from that ComboBox and add them into a ListBox (via add/remove buttons). Would I be able to get away with using an ObservableCollections to hold the database values to bind to the ComboBox, since it implements INotifyPropertyChanged (and CollectionChanged)? Sorry if this is a basic question, I starting learning WPF about a month ago.

I've read over the article (very well done) by Sacha Barber.

And I've looked over the MSDN page on ObservableCollection.

What would be the advantages/disadvantages of using an ObservableCollection vs a List (which I know does not implement INotifyPropertyChanged)?

回答1:

If the items in your combobox don't change (i.e. you don't add/remove/update items), then List will probably be OK for your needs (ObservableCollection will be too) if you manually notify that your List property changed when you affect it.

public List<X> MyList
{
    get
    {
        ...
    }

    set
    {
        if (... != value)
        {
            ... = value;
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs("MyList"));
            }
        }
    }
}

....

this.MyList = new List<X> { new X(...), new X(...) };

If you plan to add/remove or update items in your combobox (without creating a new MyList object, i.e. using this.MyList.Add(...)), then use ObservableCollection that is able to notify when the collection is updated (so it can update bindings).

回答2:

Something you may want to note.

Don't confuse the ObservableCollection's implementation of INotifyPropertyChanged with the objects it contain's implementation.

If one of the properties of one of the objects within the ObservableCollection changes, the UI will not reflect it unless that object implements INotifyPropertyChanged as well. Do not expect the ObservableCollection to take care of this for you.

来源：https://stackoverflow.com/questions/9790455/implementing-inotifypropertychanged-with-observablecollection

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