ComboBox SelectedItem is not showing its value

I have a ComboBox and its ComboBoxItem are all generated in run time (programmatically). Whenever there a ComboBox.SelectionChange, the program will show a MessageBox showing the selected content of the ComboBox

private void cb2_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    MessageBox.Show(cb2.SelectedItem.ToString());
}

However, it is show me:

System.Windows.Controls.ComboBoxItem: Hello World

I only want to show "Hello World" but not the "System...." thing. I tried SelectedValue and that's showing the same thin开发者_StackOverflow中文版g as well.

You need to cast the selected item to a ComboBoxItem and only get its content.

MessageBox.Show((cb2.SelectedItem as ComboBoxItem).Content.ToString());

You should consider using bindings rather than event handlers. This leads to much cleaner code and greater separation of concerns between presentation and process:

Declare your combo as follows:

<ComboBox x:Name="cboCountries" DisplayMemberPath="Name" SelectedItem="{Binding SelectedCountry}" ItemsSource="{Binding Countries}" />

You then bind your ComboBox to a collection on your Window (or preferably a ViewModel):

public Window1()
{
    InitializeComponent();

    DataContext = this;

    this.Countries = new ObservableCollection<Country>();
    this.Countries.Add(new Country {Id = 1, Name = "United Kingdom" });
    this.Countries.Add(new Country {Id = 1, Name = "United States" });
}

public ObservableCollection<Country> Countries {get; set;}

private Country selectedCountry;

public Country SelectedCountry
{
    get { return this.selectedCountry; }
    set 
    {
        System.Diagnostics.Debug.WriteLine(string.Format("Selection Changed {0}", value.Name));
        this.selectedCountry = value;
    }
}

The binding expression on the SelectedValue property of the Combo will cause the property setter on SelectedCountry to fire whenever the selected item changes in the combo.

public class Country
{
    public int Id { get; set;}

    public string Name {get; set;}
}