Why does not show notification on Android 9

Question

Does not show notification on Android 9.0 and works great on 8 and below. I had trouble with old code and I read that is needed to pass Channel on new android version, I got this code from internet but still is not working on Android 9.0. I don't know why. Any help will be appreciated.

As I read through internet everything looks good. But notification does not show.

    private void showSmallNotification( int icon, String title, String message, String timeStamp, PendingIntent resultPendingIntent){
        String CHANNEL_ID = Constants.ChannelID;
        String CHANNEL_NAME = "Notification";

        NotificationManager notificationManager = (NotificationManager) this.getSystemService(Context.NOTIFICATION_SERVICE);;
        NotificationCompat.Builder notification;
        NotificationCompat.InboxStyle inboxStyle = new NotificationCompat.InboxStyle();

        inboxStyle.addLine(message);

        if (Build.VERSION.SDK_INT >= 26) {
            NotificationChannel channel = new NotificationChannel(CHANNEL_ID, CHANNEL_NAME, NotificationManager.IMPORTANCE_HIGH);
            channel.enableVibration(true);
            channel.setLightColor(Color.BLUE);
            channel.enableLights(true);
            channel.setSound(Uri.parse(ContentResolver.SCHEME_ANDROID_RESOURCE + "://" + getApplicationContext().getPackageName() + "/" + R.raw.notification),
                    new AudioAttributes.Builder()
                            .setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
                            .setUsage(AudioAttributes.USAGE_NOTIFICATION)
                            .build());
            channel.canShowBadge();
            notificationManager.createNotificationChannel(channel);
            notification = new NotificationCompat.Builder(getApplicationContext(), CHANNEL_ID);
        } else {
            notification = new NotificationCompat.Builder(getApplicationContext(),CHANNEL_ID);
        }
        notification
                .setVibrate(new long[]{0, 100})
                .setPriority(Notification.PRIORITY_MAX)
                .setLights(Color.BLUE, 3000, 3000)
                .setAutoCancel(true)
                .setContentTitle(title)
                .setContentIntent(resultPendingIntent)
                .setWhen(getTimeMilliSec(timeStamp))
                .setSmallIcon(R.mipmap.ic_launcher)
                .setStyle(inboxStyle)
                .setLargeIcon(BitmapFactory.decodeResource(this.getResources(), icon))
                .setContentText(message)
                .build();

        notificationManager.notify(CHANNEL_ID, 1, notification.build());
    }

Answer 1

I think the problem is you did not setChannelId() on the notificationBuilder. (I took the liberty to rename notification to notificationBuilder since that is what it is.)

I removed an superfluous semi-colons in one of the lines of code.

Also note that canShowBadge() is a class method that returns a value, but does not set any notification settings. I replaced it with setShowBadge(true).

Please read the comments I left in the code fragment for additional information.

private void showSmallNotification( int icon, String title, String message, String timeStamp, PendingIntent resultPendingIntent){
        String CHANNEL_ID = Constants.ChannelID;
        String CHANNEL_NAME = "Notification";

        // I removed one of the semi-colons in the next line of code
        NotificationManager notificationManager = (NotificationManager) this.getSystemService(Context.NOTIFICATION_SERVICE);
        NotificationCompat.InboxStyle inboxStyle = new NotificationCompat.InboxStyle();

        inboxStyle.addLine(message);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            // I would suggest that you use IMPORTANCE_DEFAULT instead of IMPORTANCE_HIGH
            NotificationChannel channel = new NotificationChannel(CHANNEL_ID, CHANNEL_NAME, NotificationManager.IMPORTANCE_HIGH);
            channel.enableVibration(true);
            channel.setLightColor(Color.BLUE);
            channel.enableLights(true);
            channel.setSound(Uri.parse(ContentResolver.SCHEME_ANDROID_RESOURCE + "://" + getApplicationContext().getPackageName() + "/" + R.raw.notification),
                    new AudioAttributes.Builder()
                            .setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
                            .setUsage(AudioAttributes.USAGE_NOTIFICATION)
                            .build());
            //channel.canShowBadge();
            // Did you mean to set the property to enable Show Badge?
            channel.setShowBadge(true);
            notificationManager.createNotificationChannel(channel);
        }

        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(getApplicationContext(), CHANNEL_ID)
            .setVibrate(new long[]{0, 100})
            .setPriority(Notification.PRIORITY_MAX)
            .setLights(Color.BLUE, 3000, 3000)
            .setAutoCancel(true)
            .setContentTitle(title)
            .setContentIntent(resultPendingIntent)
            .setWhen(getTimeMilliSec(timeStamp))
            .setSmallIcon(R.mipmap.ic_launcher)
            .setStyle(inboxStyle)
            .setLargeIcon(BitmapFactory.decodeResource(this.getResources(), icon))
            .setContentText(message);
        // Removed .build() since you use it below...no need to build it twice

        // Don't forget to set the ChannelID!!
        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O){
            notificationBuilder.setChannelId(ID_SPECIAL_OFFER_NOTIFICATION);
        }

        notificationManager.notify(CHANNEL_ID, 1, notificationBuilder.build());
    }