In Android's NotificationListenerService, the RankingMap provides access to the importance and ranking of notifications, but it does not directly expose the NotificationChannelGroup for a StatusBarNotification. The RankingMap primarily contains metadata like importance, visibility, and other ranking-related details, but it does not include the NotificationChannelGroup information.

Key Points:

1. NotificationListenerService.RankingMap:

   • Provides access to the Notification object (via getNotification()) and its ranking metadata.
   • Does not include NotificationChannelGroup directly.

2. StatusBarNotification:

   • Contains the Notification object, which has a getChannelId() method to retrieve the channel ID.
   • The NotificationChannel itself can be retrieved using NotificationManager.getNotificationChannel(channelId).
   • However, NotificationChannel has a getGroup() method to retrieve the NotificationChannelGroup it belongs to.

3. NotificationManager:

   • Required to fetch the NotificationChannel (and thus its group) using the channel ID from the Notification object.
   • Without NotificationManager, you cannot directly access the NotificationChannelGroup.

Workaround (Without NotificationManager):

If you absolutely cannot use NotificationManager, you might need to:

• Cache the NotificationChannelGroup mappings in your app (e.g., during app initialization or when channels are created).
• Use reflection (not recommended due to fragility and compatibility issues) to access internal Android APIs, but this is risky and may break in future Android versions.

Example (With NotificationManager):

If you can use NotificationManager, here’s how you’d retrieve the NotificationChannelGroup:

// Inside your NotificationListenerService
@Override
public void onNotificationPosted(StatusBarNotification sbn, RankingMap rankingMap) {
    Notification notification = sbn.getNotification();
    if (notification != null) {
        String channelId = notification.getChannelId();
        NotificationManager notificationManager = getSystemService(NotificationManager.class);
        NotificationChannel channel = notificationManager.getNotificationChannel(channelId);
        if (channel != null) {
            NotificationChannelGroup group = channel.getGroup();
            // Use the group
        }
    }
}

Conclusion:

No, you cannot reliably retrieve the NotificationChannelGroup for a StatusBarNotification using only NotificationListenerService.RankingMap and without NotificationManager. The NotificationManager is required to fetch the channel and its group. If you cannot use it, you’ll need to rely on pre-cached data or other workarounds.