android:name=".App"

package eu.lepiller.nani;

import android.app.Application;

import android.app.NotificationChannel;

import android.app.NotificationManager;

public class App extends Application {

    public static final String DICTIONARY_DOWNLOAD_NOTIFICATION_CHANNEL = "dictionaryDownloadChannel";

    @Override

    public void onCreate() {

        super.onCreate();

        createNotificationChannel();

    }

    private void createNotificationChannel() {

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

            NotificationChannel channel = new NotificationChannel(DICTIONARY_DOWNLOAD_NOTIFICATION_CHANNEL,

                    "Nani's dictionary download notification", NotificationManager.IMPORTANCE_DEFAULT);

            NotificationManager manager =

                    (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

            if(manager != null)

                manager.createNotificationChannel(channel);

        }

    }

}