Firebase android show notification on new item added using a service

AndroidManifest.xml

<application>
<service
            android:name=".updates.BackroundLUpdateService"
            android:enabled="true"
            android:exported="true"></service>
</application>

BackroundLUpdateService.java

import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.IBinder;
import android.preference.PreferenceManager;
import android.support.v4.app.NotificationCompat;
import android.util.Log;

import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.Query;
import com.google.firebase.database.ValueEventListener;

import java.util.ArrayList;

public class BackroundLUpdateService extends Service {

    SharedPreferences settingsPref;

    public BackroundLUpdateService() {
    }


    @Override
    public void onCreate() {
        super.onCreate();
        settingsPref = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
        sessionManager = new SessionManager(getApplicationContext());
        // show notification
        final ArrayList<Notes> notes = new ArrayList<>();
        final DatabaseReference reference = FirebaseDatabase.getInstance().getReference().child("updates").child("Kenya");

  

        Query items = reference.orderByChild("timestamp").limitToLast(1);
        items.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot snapshot) {
                //note information

                for (DataSnapshot items : snapshot.getChildren()) {
                    Updates values = items.getValue(Updates.class);

                    //show notification
                    if (values != null) {
                        showNotif(values.name, values.location, values.note);
                    }
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO: Return the communication channel to the service.
        throw new UnsupportedOperationException("Not yet implemented");
    }


    private void showNotif(String name, String place, String note)

    {
        if (settingsPref.getBoolean("notifications_new_update", true)) {
            //push a notification
            Intent intent = new Intent(getApplicationContext(), MapActivity.class);
            PendingIntent contentIntent = PendingIntent.getActivity(getApplicationContext(), 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);

            NotificationCompat.Builder b = new NotificationCompat.Builder(getApplicationContext(), null);

            b.setAutoCancel(true)
                    .setDefaults(Notification.DEFAULT_ALL)
                    .setWhen(System.currentTimeMillis())
                    .setSmallIcon(R.drawable.ic_action_notif)
                    .setContentTitle("Updates")
                    .setContentText(name + " check " + place + " :" + note)
                    .setDefaults(Notification.DEFAULT_LIGHTS | Notification.DEFAULT_SOUND)
                    .setContentIntent(contentIntent)
                    .setContentInfo("info");


            NotificationManager notificationManager = (NotificationManager) getApplicationContext().getSystemService(Context.NOTIFICATION_SERVICE);
            notificationManager.notify(1, b.build());
        }

    }

}

MainActivity.java

//add on create

 Intent serviceIntent = new Intent(context, BackroundLUpdateService.class);
        context.startService(serviceIntent);