在WPF Combobox中显示特定值

Question

In my combobox i have added ItemsSource which is a collection of SelectedItem. How to display any item by default in the combobox while loading the screen?

Answer 1

Are you looking for a way to select first item by default? If so, try this code:

<ComboBox SelectedIndex="0">

Otherwise, you should create a property to store currently selected item and bind to it:

<ComboBox ItemsSource="{Binding Items}" SelectedItem="{Binding CurrentlySelectedItem}">

Answer 2

If you are using a binding ie

<ComboBox ItemsSource="{Binding SlowLoadingCollection}"/>

then you can add a FallbackValue that will be used when the collection cannot be accessed.

<ComboBox ItemsSource="{Binding SlowLoadingCollection, FallbackValue='Please wait'}"/>

you can test this with something like

DataContext.SlowLoadingCollection = null; // No collection, so will display fallback
this.OnLoaded += () =>
{
   Task.Run(()=>
   {
      Task.Delay(10000); // 10 second delay to simulate loading
      DataContext.SlowLoadingCollection = new []{ "Hello", "World", "!"};
   }
}