foreground_service.java

public class NotificationService extends Service {

    private static final int ID_SERVICE = 101;

    @Nullable @Override public IBinder onBind(Intent intent) {
        return null;
    }

    @Override public void onCreate() {
        super.onCreate();
        NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        String channelId = createNotificationChannel(notificationManager);
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, channelId);
        
        Notification notification = notificationBuilder.setOngoing(true)
                .setContentTitle("Navigine Service Example")
                .setCategory(NotificationCompat.CATEGORY_SERVICE)
                .build();

        startForeground(ID_SERVICE, notification);
    }

    @Override public int onStartCommand(Intent intent, int flags, int startId) {
        super.onStartCommand(intent, flags, startId);
        return START_REDELIVER_INTENT;
    }

    private String createNotificationChannel(NotificationManager notificationManager){
        String channelId = "NAVIGINE_SERVICE_CHANNEL_ID_EXAMPLE";
        String channelName = "NAVIGINE CHANNEL NAME EXAMPLE";
        NotificationChannel channel = new NotificationChannel(channelId, 
                                                              channelName, 
                                                              NotificationManager.IMPORTANCE_HIGH);
        channel.setLockscreenVisibility(Notification.VISIBILITY_PUBLIC); // will be shown in lock screen
        notificationManager.createNotificationChannel(channel);
        return channelId;
    }
}