private static String HOUR = "hour";
private static String MINUTE = "minute";


public static void setAlarm(Context context, int hour, int minute){
    SharedPreferences preferences =  PreferenceManager.getDefaultSharedPreferences(context);
    preferences.edit()
            .putInt(HOUR, hour)
            .putInt(MINUTE, minute)
            .apply();
    setAlarm(context);
}



private static void setAlarm(Context context) {

    int hour = getHour(context);
    int minute = getMinute(context);

    if(hour == -1 || minute == -1){
        //nenhum horário definido
        return;
    }

    // Cria um Calendar para o horário estipulado
    Calendar calendar = Calendar.getInstance();
    calendar.set(Calendar.HOUR_OF_DAY, hour);
    calendar.set(Calendar.MINUTE, minute);

    //Se já passou
    if(isDateBeforeNow(calendar)){
        //adiciona um dia
        calendar.add(Calendar.DAY_OF_MONTH, 1);
    }


    //PendingIntent para lançar o serviço
    Intent serviceIntent = new Intent(context, BootService.class);
    PendingIntent pendingIntent = PendingIntent.getService(context, 0, serviceIntent, 0);

    AlarmManager alarmManager = (AlarmManager)context.getSystemService(Context.ALARM_SERVICE);
    //Cancela um possível alarme existente
    alarmManager.cancel(pendingIntent);

    //Alarme que se repete todos os dias a uma determinada hora
    alarmManager.setInexactRepeating(AlarmManager.RTC_WAKEUP,
            calendar.getTimeInMillis(),
            AlarmManager.INTERVAL_DAY,
            pendingIntent);
}

private static int getHour(Context context){
    SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
    return preferences.getInt(HOUR, -1);
}
private static int getMinute(Context context){
    SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
    return preferences.getInt(MINUTE, -1);
}

private static boolean isDateBeforeNow(Calendar calendar){
    return calendar.getTimeInMillis() <= System.currentTimeMillis();
}

@Override
public void onReceive(Context context, Intent intent) {


        if (Intent.ACTION_BOOT_COMPLETED.equals(intent.getClass())) {
            setAlarm(context);
            Toast.makeText(context, "Alarm set", Toast.LENGTH_LONG).show();
        }

    }
}

private PowerManager.WakeLock wakeLock;

    public BootService() {
        super("name");
    }

    @Override
    public void onCreate() {
        super.onCreate();

        PowerManager pm = (PowerManager) this.getSystemService(Context.POWER_SERVICE);
        wakeLock = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK |
                PowerManager.ACQUIRE_CAUSES_WAKEUP |
                PowerManager.ON_AFTER_RELEASE, "BootService");
        wakeLock.acquire();
    }

    @Override
    protected void onHandleIntent(@Nullable Intent intent) {

        //Lance a notificação aqui.
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if(wakeLock.isHeld()){
            //Verificou-se que o iluminar do ecrã
            //não acontecia devido ao WakeLock ser
            //rapidamente libertado(apesar de PowerManager.ON_AFTER_RELEASE !?).
            try {
                //Atrasa a libertação do WakeLock
                //de forma a permitir a iluminação do ecrâ.
                Thread.sleep(5000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            finally {
                wakeLock.release();
            }
        }
    }