Bdtjtk

I get Toast on Android 8.1 API 27:

Developer warning for package "my_package_name"

Failed to post notification on ...

Logcat includes next strings:

Notification: Use of stream types is deprecated for operations other
than volume control

W/Notification: See the documentation of setSound() for what to use
instead with android.media.AudioAttributes to qualify your playback
use case

E/NotificationService: No Channel found for pkg=my_package_name

The full information in the Toast and in Logcat can help in the localization this problem.

If you get this error should be paid attention to 2 items and them order:

1. NotificationChannel mChannel = new NotificationChannel(id, name, importance);


2. builder = new NotificationCompat.Builder(context, id);

Also NotificationManager notifManager and NotificationChannel mChannel are created only once.

There are required setters for Notification:

• builder.setContentTitle() // required


• .setSmallIcon() // required


• .setContentText() // required

See example:

private NotificationManager notifManager;

public void createNotification(String aMessage, Context context) {

    final int NOTIFY_ID = 0; // ID of notification

    String id = context.getString(R.string.default_notification_channel_id); // default_channel_id

    String title = context.getString(R.string.default_notification_channel_title); // Default Channel

    Intent intent;

    PendingIntent pendingIntent;

    NotificationCompat.Builder builder;

    if (notifManager == null) {

        notifManager = (NotificationManager)context.getSystemService(Context.NOTIFICATION_SERVICE);

    }

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {

        int importance = NotificationManager.IMPORTANCE_HIGH;

        NotificationChannel mChannel = notifManager.getNotificationChannel(id);

        if (mChannel == null) {

            mChannel = new NotificationChannel(id, title, importance);

            mChannel.enableVibration(true);

            mChannel.setVibrationPattern(new long{100, 200, 300, 400, 500, 400, 300, 200, 400});

            notifManager.createNotificationChannel(mChannel);

        }

        builder = new NotificationCompat.Builder(context, id);

        intent = new Intent(context, MainActivity.class);

        intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);

        pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);

        builder.setContentTitle(aMessage)                            // required

               .setSmallIcon(android.R.drawable.ic_popup_reminder)   // required

               .setContentText(context.getString(R.string.app_name)) // required

               .setDefaults(Notification.DEFAULT_ALL)

               .setAutoCancel(true)

               .setContentIntent(pendingIntent)

               .setTicker(aMessage)

               .setVibrate(new long{100, 200, 300, 400, 500, 400, 300, 200, 400});

    }

    else {

        builder = new NotificationCompat.Builder(context, id);

        intent = new Intent(context, MainActivity.class);

        intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);

        pendingIntent = PendingIntent.getActivity(context, 0, intent, 0);

        builder.setContentTitle(aMessage)                            // required

               .setSmallIcon(android.R.drawable.ic_popup_reminder)   // required

               .setContentText(context.getString(R.string.app_name)) // required

               .setDefaults(Notification.DEFAULT_ALL)

               .setAutoCancel(true)

               .setContentIntent(pendingIntent)

               .setTicker(aMessage)

               .setVibrate(new long{100, 200, 300, 400, 500, 400, 300, 200, 400})

               .setPriority(Notification.PRIORITY_HIGH);

    }

    Notification notification = builder.build();

    notifManager.notify(NOTIFY_ID, notification);

}

Andy's answer is working however I wanted to avoid to deprecated Builder and follow the FireBase Quickstart Project. I just added code before notify from manager.

String channelId = "default_channel_id";

String channelDescription = "Default Channel";

// Since android Oreo notification channel is needed.

//Check if notification channel exists and if not create one

if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {

    NotificationChannel notificationChannel = notificationManager.getNotificationChannel(channelId);

    if (notificationChannel == null) {

        int importance = NotificationManager.IMPORTANCE_HIGH; //Set the importance level

        notificationChannel = new NotificationChannel(channelId, channelDescription, importance);

        notificationChannel.setLightColor(Color.GREEN); //Set if it is necesssary

        notificationChannel.enableVibration(true); //Set if it is necesssary

        notificationManager.createNotificationChannel(notificationChannel);

    }

}



//notificationManager.notify as usual

Edit:
They removed the channel exist check from example I am not sure why.

I have set channel id, but notification still not shown.

Finally i found my problem is had not invoke "setContentText()" method.

It was really help me that @Andy Sander mentioned "required setters"!

here are required setters for Notification on Android 8 Oreo API 26 and later:

builder.setContentTitle() // required

.setSmallIcon() // required

.setContentText() // required

.setChannelId(id) // required for deprecated in API level >= 26 constructor .Builder(this)

Also don't forget to bind your channel_id to your notification builder. After binding it, my problem gone.

notificationBuilder.setChannelId(channelId)

or

NotificationCompat.Builder(Context context, String channelId)