Как правильно настроить Notification в андроид проекте?

У меня имеется небольшое приложение, которое выполняет роль Task Manager'a. Попробовал настроить уведомление по конкретной дате (то есть выставляю дату через DataPickerDialog) и хотелось бы чтобы приходило уведомление в назначенный день, чего собственно не происходит. Прошу помочь разобраться в проблеме

NoteActivity:

public class NoteActivity extends AppCompatActivity {

    private static final String EXTRA_NOTE = "NoteActivity.EXTRA_NOTE";
    public static final String NOTIFICATION_CHANNEL_ID = "10001" ;
    private final static String default_notification_channel_id = "default" ;
    final Calendar myCalendar = Calendar. getInstance () ;

    private Note note;
    private EditText etTitle;
    private EditText etDesc;
    private TextView tvDateOfCreate;
    private Button btnDate;

    int DIALOG_DATE = 1;
    int myYear = 2021;
    int myMonth = 1;
    int myDay = 1;

    SimpleDateFormat sdf = new SimpleDateFormat("HH:mm, dd-MM-yyyy");

    public static void start(Activity caller, Note note) {
        Intent intent = new Intent (caller, NoteActivity.class);
        if (note != null) {
            intent.putExtra(EXTRA_NOTE, note);
        }
        caller.startActivity(intent);
    }

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_note);
        Toolbar toolbar = findViewById(R.id.toolbarNote);

        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setHomeButtonEnabled(true);

        setTitle(getString(R.string.note_create));

        etTitle = findViewById(R.id.etTitle);
        etDesc = findViewById(R.id.etDesc);
        tvDateOfCreate = findViewById(R.id.tvDateOfCreateNote);
        btnDate = findViewById(R.id.btnDate);

        if (getIntent().hasExtra(EXTRA_NOTE)) {
            note = getIntent().getParcelableExtra(EXTRA_NOTE);
            btnDate.setVisibility(View.INVISIBLE);
            etTitle.setText(note.title);
            etDesc.setText(note.text);
            tvDateOfCreate.setText("Дата создания заметки: " + note.date);
            tvDateOfCreate.setVisibility(View.VISIBLE);
        } else {
            note = new Note();
        }
    }

    private void scheduleNotification (Notification notification , long delay) {
        Intent notificationIntent = new Intent( this, MyNotificationPublisher. class ) ;
        notificationIntent.putExtra(MyNotificationPublisher. NOTIFICATION_ID , 1 ) ;
        notificationIntent.putExtra(MyNotificationPublisher. NOTIFICATION , notification) ;
        PendingIntent pendingIntent = PendingIntent. getBroadcast ( this, 0 ,
                notificationIntent , PendingIntent. FLAG_UPDATE_CURRENT ) ;
        AlarmManager alarmManager = (AlarmManager) getSystemService(Context. ALARM_SERVICE ) ;
        assert alarmManager != null;
        alarmManager.set(AlarmManager. ELAPSED_REALTIME_WAKEUP , delay , pendingIntent) ;
    }
    private Notification getNotification (String content) {
        NotificationCompat.Builder builder = new NotificationCompat.Builder( this,
                default_notification_channel_id ) ;
        builder.setContentTitle( "Scheduled Notification" ) ;
        builder.setContentText(content) ;
        builder.setSmallIcon(R.mipmap.ic_launcher ) ;
        builder.setAutoCancel( true ) ;
        builder.setChannelId( NOTIFICATION_CHANNEL_ID ) ;
        return builder.build() ;
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_note, menu);
        return super.onCreateOptionsMenu(menu);
    }

    @SuppressLint("NonConstantResourceId")
    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                finish();
                break;
            case R.id.action_save:
                if ((etDesc.getText().length() > 0) && (etTitle.getText().length() > 0)) {
                    note.title = etTitle.getText().toString();
                    note.text = etDesc.getText().toString();
                    note.done = false;
                    note.plannedDay = btnDate.getText().toString();
                    note.date = sdf.format(Calendar.getInstance().getTime());
                    note.timestamp = System.currentTimeMillis();
                    if (getIntent().hasExtra(EXTRA_NOTE)) {
                        App.getInstance().getNoteDao().update(note);
                    } else {
                        App.getInstance().getNoteDao().insert(note);
                    }
                    finish();
                } else {
                    Toast.makeText(this, "Заполните поля названия и описания заметки",
                            Toast.LENGTH_SHORT).show();
                }
                break;
        }
        return super.onOptionsItemSelected(item);
    }

    public void onChangeDate(View view) {
        showDialog(DIALOG_DATE);
    }


    protected Dialog onCreateDialog(int id) {
        if (id == DIALOG_DATE) {
            DatePickerDialog tpd = new DatePickerDialog(this, myCallBack, myYear, myMonth, myDay);
            return tpd;
        }
        return super.onCreateDialog(id);
    }

    DatePickerDialog.OnDateSetListener myCallBack = new DatePickerDialog.OnDateSetListener() {

        public void onDateSet(DatePicker view, int year, int monthOfYear,
                              int dayOfMonth) {
            myYear = year;
            myMonth = monthOfYear;
            myDay = dayOfMonth;
            btnDate.setText("Задана дата " + myDay + "/" + myMonth + "/" + myYear);
            myCalendar.set(Calendar. YEAR , year) ;
            myCalendar.set(Calendar. MONTH , monthOfYear) ;
            myCalendar.set(Calendar. DAY_OF_MONTH , dayOfMonth) ;
            updateLabel();
        }
    };

    private void updateLabel () {
        Date date = myCalendar.getTime();
        scheduleNotification(getNotification(btnDate.getText().toString()) , date.getTime()) ;
    }
}

NotificationPublisher:

public class MyNotificationPublisher extends BroadcastReceiver {

    public static String NOTIFICATION_ID = "notification-id" ;
    public static String NOTIFICATION = "notification" ;

    public void onReceive (Context context , Intent intent) {
        NotificationManager notificationManager = (NotificationManager) context.getSystemService(Context. NOTIFICATION_SERVICE ) ;
        Notification notification = intent.getParcelableExtra( NOTIFICATION ) ;
        if (android.os.Build.VERSION. SDK_INT >= android.os.Build.VERSION_CODES. O ) {
            int importance = NotificationManager. IMPORTANCE_HIGH ;
            NotificationChannel notificationChannel = new NotificationChannel( NOTIFICATION_CHANNEL_ID , "NOTIFICATION_CHANNEL_NAME" , importance) ;
            assert notificationManager != null;
            notificationManager.createNotificationChannel(notificationChannel) ;
        }
        int id = intent.getIntExtra( NOTIFICATION_ID , 0 ) ;
        assert notificationManager != null;
        notificationManager.notify(id , notification) ;
    }
}

Уже думал, может как то через Firebase (FCM) организовать, но не знаю, как это правильно сделать.