Notifications on Android Automotive OS

Notifications provide drivers with short, timely information about events from your app while it's not in use. Notifications can appear in the Notification Center, and some notifications can also appear as heads-up notifications on the display. To create notifications for Android Automotive OS, you use the same NotificationBuilder API that you use for other devices. However, to help ensure the safety of drivers and minimize distraction, some API methods and classes are restricted or behave differently.

How notifications differ in cars

To create a safe driving environment that is free from distractions, notifications on Android Automotive OS differ from notifications on other devices in the following ways:

• Simplified user interaction
• UX restrictions based on drive state

Simplified user interaction

To help ensure that drivers can focus on the road, notifications in the car have a simplified user interaction model with the following features:

No complex controls

Notifications do not allow complex controls, such as tapping to expand a notification, long-pressing a notification for additional options, or using controls based on swipe-length gestures.

Notification sounds

Notifications only play a sound if they trigger a heads-up notification.

Automatic play and mute buttons for messaging notifications

Android Automotive OS automatically adds Play and Mute buttons to all car-compatible messaging notifications.

• Play: reads the notification to the driver using the user's default digital assistant, such as the Google Assistant, or the vehicle's default text-to-speech system.

• Mute: prevents heads-up notifications from appearing for any future messages in the conversation for the remainder of the drive. Message notifications from a muted conversation still appear in the Notification Center, and the driver can also unmute the conversation from the Notification Center.

Simplified notification display options

RemoteViews and custom content views are not supported. In addition, the following notification styles are not supported:

• BigPictureStyle
• BigTextStyle
• InboxStyle

If your app sends a notification to Android Automotive OS using one of these notification styles, only summary text is shown.

Simplified notification channel management

Android Automotive OS does not support notification channels and related UI affordances, to decrease the prevalence of rich management tasks in Automotive devices.

UX restrictions based on drive state

Android Automotive OS includes a UX Restrictions Engine. Car manufacturers can use this engine to restrict notifications based on the car's drive state in the following ways:

• Truncating notification strings at a specific character length
• Hiding message summaries for CATEGORY_MESSAGE notifications
• Limiting the number of notifications that the Notification Center can display

Supported resource types

By default, Android Automotive OS supports a limited subset of the resource types that can be used for notifications on other devices. This subset includes the following resource types:

• Drawables
• Icons
• Images

Compatibility requirements for messaging notifications

To provide a consistent and minimally distracting user experience, messaging notifications have special requirements on Android Automotive OS.

A messaging notification is car-compatible if it fulfills the following requirements:

• It belongs to the CATEGORY_MESSAGE category.
• It uses the Notification.MessagingStyle style.
• It includes only unread messages.

• It has a mark-as-read Action that fulfills the following requirements:

  • The semantic action is set to Action.SEMANTIC_ACTION_MARK_AS_READ.
  • The Action indicates that it does not show any user interface when fired.

• If the notification has a reply Action, then the Action fulfills the following requirements:

  • The semantic action is set to Action.SEMANTIC_ACTION_REPLY.
  • The Action indicates that it does not show any user interface when fired.
  • The Action contains a single RemoteInput.

Notification Center

Almost all notifications appear in the Notification Center, even if those notifications were also triggered as heads-up notifications. Notifications persist in the Notification Center for the duration of a drive.

Drivers can interact with notifications in the Notification Center. Depending on the car's manufacturer, drivers access the Notification Center in one or both of the following ways:

• Swiping down from the top of the screen, similar to the notification drawer on other devices.
• Tapping a button in the system interface.

Grouped notifications

Related notifications are automatically grouped in the Notification Center, as in the notification drawer on other devices. However, when a driver taps the summary for a group in the Notification Center, instead of launching a PendingIntent, the group expands to show all of its notifications.

Notifications that do not appear in the Notification Center

The following notifications do not appear in the Notification Center:

• Media playback notifications. Information about ongoing media playback is gathered by Android Automotive OS and displayed in a dedicated place in the user interface. Note that setMediaSession must be called with a non null token for the notification to be recognized as Media playback.
• Turn-by-turn navigation notifications for CATEGORY_NAVIGATION.
• Foreground service notifications for system privileged apps and apps that are signed with the platform key that have an importance level lower than IMPORTANCE_DEFAULT.

Heads-up notifications

Heads-up notifications appear as a notification card on top of the screen. Because a heads-up notification draws the driver's attention, only trigger a heads-up notification when the information is drive-critical, time sensitive, and actionable. Only certain categories of notifications can trigger a heads-up notification.

Car manufacturers can decide whether to permit heads-up notifications to appear while the Notification Center is open.

How apps trigger heads-up notifications

Apps have different requirements for triggering a heads-up notification depending on whether they have system privileges.

System-privileged apps and apps signed with the platform key

The app can trigger a heads-up notification by setting the notification channel importance to IMPORTANCE_HIGH or higher.

All other apps

The app can trigger a heads-up notification by setting the notification channel importance to IMPORTANCE_HIGH or higher and ensuring that the notification belongs to one of the following categories:

• CATEGORY_CALL
• CATEGORY_MESSAGE
• CATEGORY_NAVIGATION

Life of a heads-up notification

After an app triggers a heads-up notification, the notification appears immediately on the car's screen. If the driver takes no action, the heads-up notification dismisses automatically after eight seconds, except in the following cases:

• Heads-up notifications for certain incoming calls cannot be dismissed, and the heads-up notification remains until either the driver accepts the call or the call is terminated. To qualify as an undismissable heads-up notification for an incoming call, a notification must fulfill the following requirements:

  • Belong to CATEGORY_CALL
  • Set a fullscreen intent
  • Be marked as ongoing using the setOngoing() method

• Heads-up notifications remain if an app updates the notification within the eight-second time window.

When a heads-up notification is dismissed, the notification is listed in the Notification Center, unless it is a CATEGORY_NAVIGATION notification.

Notification API changes and restrictions for cars

This section summarizes the differences for each class where the Notifications API behaves differently or has restrictions for Android Automotive OS.

Notification.Builder

Tables 1 and 2 describe the API changes and restrictions in the Notification.Builder class.

Table 1. Changes to public methods for Notification.Builder

Public methods	Effect	Description
addAction()	Conditional no-op	Notification.MessagingStyle notifications must add the actions specified in the compatibility requirements. Any additional actions that are added will not be rendered as Notification buttons.
createBigContentView() createContentView() createHeadsUpContentView() setContent() setCustomBigContentView() setCustomContentView() setCustomHeadsUpContentView()	No-op	RemoteViews and custom content views are not supported.
setBadgeIconType() setNumber()	No-op	Notification badges are not supported.
setChronometerCountDown() setUsesChronometer()	No-op	Countdown timers are not supported.
setColorized()	Constraints changed	Platform-signed apps: configurable; allowed by default. System-privileged apps: configured by platform; disallowed by default. All other apps: configured by platform; disallowed by default.
setFullScreenIntent()	Behavior changed	Does not auto-launch the intent.
setLargeIcon()	Behavior changed	Large icons are shown on the righthand side of the notification.
setLights()	No-op	Android Automotive OS devices do not have LED indicator lights.
setOngoing()	Behavior changed	Behavior is different when the notification also triggers a heads-up notification. setOngoing() only makes the heads-up notification undismissable if the heads-up notification is for an incoming call. To qualify as an undismissable heads-up notification for an incoming call, a notification must fulfill setPublicVersion() setVisibility()	No-op	Private mode is not supported.
setSettingsText()	No-op	Notifications do not support affordances that link to app settings. Drivers access app settings through the app instead.
setTicker()	No-op	Ticker text is not supported.

Table 2. Changes to nested classes for Notification.Builder

Nested classes	Effect	Description
Notification.BigPictureStyle Notification.BigTextStyle Notification.InboxStyle	Not used	Only summary text shows. Detailed notifications for these styles are not supported.
Notification.BubbleMetadata	Not used	Bubbles are not supported.
Notification.MediaStyle	Hidden	Notifications with this style are hidden. Android Automotive OS manages user interface interactions for media notifications and playback.
Notification.MessagingStyle	Behavior changed	Notifications with this style have the following differences: Notifications only show the last message from a conversation when using addMessage(). Only unread messages are included, as specified in the compatibility requirements. Android Automotive OS automatically adds Play and Mute buttons to car-compatible messaging notifications. Notifications must add the actions specified in the compatibility requirements. Any additional actions that are added are not rendered as Notification buttons.
Notification.CarExtender Notification.WearableExtender	Not used	Extenders are not supported.

Notification.Action.Builder

Table 3 describes the API changes and restrictions in the Notification.Action.Builder class.

Table 3. Changes to public methods for Notification.Action.Builder

Public methods	Effect	Description
Public constructors	Behavior changed	Icons specified in public constructors are ignored.
addRemoteInput	Behavior changed	To minimize driver distraction, a digital assistant, such as the Google Assistant, inserts the response to a message for the user. Users can't type messages.
setAllowGeneratedReplies	No-op	Smart Reply is not supported.