Creating a notification with notification channel gives no effect

Question

I've been browsing the net for an answer but i can't find it myself despite reading the developer guides on the official android documentation site and code snippets from all over the Internet.

I've been practicing creating notifications on a new clean project, and despite creating a notification channel and the notification itself I still can't get it to run and get a message saying: "Failed to post notification on null channel". But im creating the channel, and assigning it to my notification just like it says everywhere. Im completely out of ideas and honestly i've been browsing stack for at least few hours now and every answer looks the same but it really didn't help me at all, so maybe if someone who's better than a begginer looks at my code can tell me what's wrong with my code? It's annoying because notifications are an important part of a project im working on, and it stopped me in my tracks.

public class MainActivity extends AppCompatActivity {


NotificationCompat.Builder notification;
private static final int NOTIFICATION_ID = 1;
private static final String NOTIFICATION_CHANNEL_ID = "my_notification_channel";



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    notification = new NotificationCompat.Builder(this);
    notification.setAutoCancel(true);


    findViewById(R.id.buckysButton).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            createNotification(view);
        }
    });


}

public void createNotification(View view){
    NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        NotificationChannel notificationChannel = new NotificationChannel(NOTIFICATION_CHANNEL_ID, "My Notifications", NotificationManager.IMPORTANCE_DEFAULT);
        notificationChannel.setDescription("Channel description");
        notificationChannel.enableLights(true);
        notificationChannel.setLightColor(Color.RED);
        notificationChannel.setVibrationPattern(new long[]{0, 1000, 500, 1000});
        notificationChannel.enableVibration(true);
        nm.createNotificationChannel(notificationChannel);
    }
        notification.setSmallIcon(R.drawable.ic_priority_high_black_24px);
        notification.setTicker("Ticker");
        notification.setWhen(System.currentTimeMillis());
        notification.setContentTitle("Title");
        notification.setContentText("Body Body Body Body Body Body Body Body Body ");
        notification.setChannel(NOTIFICATION_CHANNEL_ID);
        notification.build();

        Intent intent = new Intent(this, MainActivity.class);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
        notification.setContentIntent(pendingIntent);

        nm.notify(NOTIFICATION_ID, notification.build());
    }}

By the way I'm developing for Android minimum level of 5.1 and I have been wondering if it's really necessary to put channels in my application, but I did it anyways since when im trying to do it without them I'm still getting exactly the same error.

EDIT: Im still struggling with this issue. Do I have to do something in the gradle files to be able to pass two arguments into the NotificationCompat.Builder constructor? It wont let me do it no matter what i do, i think thats the main problem here.

NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID)

Doesnt do it for me, it still doesnt want to take the channel_id as an argument.

Answer 1

Ok, maybe I'm bit late, but...

Try to shorten your channelId string.

Now it

private static final String NOTIFICATION_CHANNEL_ID = "my_notification_channel";

Try

private static final String NOTIFICATION_CHANNEL_ID = "my_channel";

For me it was a very strange bug. When channelId was too long it don't show notification on my device.

Edit:

It was not too long or too short, just some string got banned in system. Also it not showed in Android notification settings screen.

Answer 2

I've found out what was missing. I was using android studio 2.3.3 instead of the newest 3.0.1 so I couldn't import some of the new functions through Gradle.

After that i only had to change my dependencies classpath to 'com.android.tools.build:gradle:3.0.1' and the problem was gone.

Thanks for help.

Answer 3

new NotificationCompat.Builder(this);

is deprecated, try using

NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID)

Here's a sample code, create a NotificationHelper class as follows,

import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.content.Context;
import android.content.ContextWrapper;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.provider.Settings;
import android.support.v4.app.NotificationCompat;
import android.support.v4.content.ContextCompat;

public class NotificationHelper extends ContextWrapper {
    private NotificationManager mNotificationManager;
    private final String MY_CHANNEL = "my_channel";
    private final long[] vibrationScheme = new long[]{200, 400};

    /**
     * Registers notification channels, which can be used later by individual notifications.
     *
     * @param context The application context
     */
    public NotificationHelper(Context context) {
        super(context);

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

            // Create the channel object with the unique ID MY_CHANNEL
            NotificationChannel myChannel =
                    new NotificationChannel(
                            MY_CHANNEL,
                            getResources().getString(R.string.notification_channel_title),
                            NotificationManager.IMPORTANCE_DEFAULT);

            // Configure the channel's initial settings
            myChannel.setLightColor(Color.GREEN);
            myChannel.setVibrationPattern(vibrationScheme);

            // Submit the notification channel object to the notification manager
            getNotificationManager().createNotificationChannel(myChannel);

        }
    }

    /**
     * Build you notification with desired configurations
     *
     */
    public NotificationCompat.Builder getNotificationBuilder(String title, String body, Intent pendingIntent) {

        Bitmap notificationLargeIconBitmap = BitmapFactory.decodeResource(
                getApplicationContext().getResources(),
                R.mipmap.ic_launcher);

        return new NotificationCompat.Builder(getApplicationContext(), MY_CHANNEL)
                .setSmallIcon(R.drawable.ic_notification_icon)
                .setLargeIcon(notificationLargeIconBitmap)
                .setContentTitle(title)
                .setContentText(body)
                .setSound(Settings.System.DEFAULT_NOTIFICATION_URI)
                .setVibrate(vibrationScheme)
                .setStyle(new NotificationCompat.BigTextStyle().bigText(body))
                .setColor(ContextCompat.getColor(getApplicationContext(), R.color.colorPrimary))
                .setContentIntent(pendingIntent)
                .setAutoCancel(true);
    }

    public NotificationManager getNotificationManager() {
        if (mNotificationManager == null) {
            mNotificationManager =
                    (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        }
        return mNotificationManager;
    }

}

and then use it as follows,

NotificationHelper notificationHelper = new NotificationHelper(context);
NotificationCompat.Builder builder = notificationHelper.getNotificationBuilder(title, message);
notificationHelper.getNotificationManager().notify(notificationID, builder.build());