CarAppExtender

public final class CarAppExtender
extends Object implements NotificationCompat.Extender

java.lang.Object
   ↳ androidx.car.app.notification.CarAppExtender


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.
  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 CarNotificationManager.notify(...) methods. Do not use the NotificationManager.notify(...), nor the NotificationManagerCompat.notify(...)} methods.
 Notification notification = new NotificationCompat.Builder(context)
         ...
         .extend(new 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:

Calling CarAppExtender.Builder.setImportance(int) will override the importance for the notification in the car screen.

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.

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).

TBT notifications behave the same as regular notifications with the following exceptions:

  • The notification will not be displayed if the navigation app is not the currently active navigation app, or if the app is already displaying routing information in the navigation template.
  • The heads-up-notification (HUN) can be customized with a background color through CarAppExtender.Builder.setColor(CarColor).
  • The notification will not be displayed in the notification center.

In addition to that, the information in the navigation notification will be displayed in the rail widget at the bottom of the screen when the app is in the background.

Note that frequent HUNs distract the driver. The recommended practice is to update the TBT notification regularly on distance changes, which updates the rail widget, but call NotificationCompat.Builder#setOnlyAlertOnce(true) unless there is a significant navigation turn event.

Summary

Nested classes

class CarAppExtender.Builder

A builder of CarAppExtender

Public constructors

CarAppExtender(Notification notification)

Creates a CarAppExtender from the CarAppExtender of an existing notification.

Public methods

NotificationCompat.Builder extend(NotificationCompat.Builder builder)

Applies car extensions to a notification that is being built.

List<Notification.Action> getActions()

Returns the list of Notification.Action present on this car notification.

String getChannelId()

Returns the channel id of the notification channel to use in the car.

CarColor getColor()

Returns the background color of the notification or null if a default color is to be used.

PendingIntent getContentIntent()

Returns the PendingIntent to send when the notification is clicked in the car or null if not set.

CharSequence getContentText()

Returns the content text of the notification or null if not set.

CharSequence getContentTitle()

Returns the content title for the notification or null if not set.

PendingIntent getDeleteIntent()

Returns the PendingIntent to send when the notification is cleared by the user or null if not set.

int getImportance()

Returns the importance of the notification in the car screen.

Bitmap getLargeIcon()

Returns the large icon bitmap to display in the notification or null if not set.

int getSmallIcon()

Returns the resource ID of the small icon drawable to use.

static boolean isExtended(Notification notification)

Returns whether the given notification was extended with CarAppExtender.

Inherited methods