CarAppExtender

public class CarAppExtender
extends Object implements NotificationCompat.Extender

Helper class to add car app extensions to notifications.

By default, notifications in a car screen have the properties provided by NotificationCompat.Builder. This helper class provides methods to override those properties for the car screen. However, notifications only show up in the car screen if it is extended with CarAppExtender, even if the extender does not override any properties. To create a notification with car extensions:

1. Create a NotificationCompat.Builder, setting any desired properties.
2. Create a CarAppExtender.Builder with builder().
3. Set car-specific properties using the set methods of CarAppExtender.Builder.
4. Create a CarAppExtender by calling CarAppExtender.Builder.build().
5. Call NotificationCompat.Builder.extend(NotificationCompat.Extender) to apply the extensions to a notification.
6. Post the notification to the notification system with the NotificationManagerCompat.notify(...) methods and not the NotificationManager.notify(...) methods.

 Notification notification = new NotificationCompat.Builder(context)
         ...
         .extend(CarAppExtender.builder()
                 .set*(...)
                 .build())
         .build();
 

Car extensions can be accessed on an existing notification by using the CarAppExtender(Notification) constructor, and then using the get methods to access values.

The car screen UI is affected by the notification channel importance (Android O and above) or notification priority (below Android O) in the following ways:

• A heads-up-notification (HUN) will show if the importance is set to NotificationManagerCompat.IMPORTANCE_HIGH, or the priority is set to NotificationCompat.PRIORITY_HIGH or above.
• The notification center icon, which opens a screen with all posted notifications when tapped, will show a badge for a new notification if the importance is set to NotificationManagerCompat.IMPORTANCE_DEFAULT or above, or the priority is set to NotificationCompat.PRIORITY_DEFAULT or above.
• The notification entry will show in the notification center for all priority levels.

Calling NotificationCompat.Builder#setOnlyAlertOnce(true) will alert a high-priority notification only once in the HUN. Updating the same notification will not trigger another HUN event.

Navigation

For a navigation app's turn-by-turn (TBT) notifications, which update the same notification frequently with navigation information, the notification UI has a slightly different behavior. The app can post a TBT notification by calling NotificationCompat.Builder#setOngoing(true) and NotificationCompat.Builder#setCategory(NotificationCompat.CATEGORY_NAVIGATION). The car screen UI is affected in the following ways:

• The same heads-up-notification (HUN) behavior as regular notifications.
• A rail widget at the bottom of the screen will show when the navigation app is in the background.

Summary

Public methods

public static CarAppExtender.Builder builder ()

public NotificationCompat.Builder extend (NotificationCompat.Builder builder)