Notification at specific time with time from sharedpreferences

I'm making an app where I want the user to specify a time in shared preferences then I'll use that time to launch a notification whether they're in the app or not, like a user-defined alarm notification.

I've tried everything but I don't know how to make it work. The notification should appear every day at that specific time if the preference (checkbox) is true.

Finally I found out how to do it. For anyone who might need the same, I'll post the code:

This here is the method to call the notification in the activity once time is right:

 public void notifyAtTime() {
    sharedPref = PreferenceManager.getDefaultSharedPreferences(this);
    long time = sharedPref.getLong("Timepref", 0);
    SimpleDateFormat formatter = new SimpleDateFormat("HH", Locale.UK);
    SimpleDateFormat formatter1 = new SimpleDateFormat("mm", Locale.UK);

    Date date = new Date(time);
    Date date1 = new Date(time);
    long hour = Long.parseLong(formatter.format(date));
    long minute = Long.parseLong(formatter1.format(date1));

    AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);

    Intent notificationIntent = new Intent("android.media.action.DISPLAY_NOTIFICATION");
    notificationIntent.addCategory("android.intent.category.DEFAULT");

    PendingIntent broadcast = PendingIntent.getBroadcast(this, 100, notificationIntent, PendingIntent.FLAG_UPDATE_CURRENT);

    Calendar cal = Calendar.getInstance();
    cal.set(Calendar.HOUR_OF_DAY, (int) hour);
    cal.set(Calendar.MINUTE, (int) minute);
    cal.set(Calendar.SECOND,0);
    if (alarmManager != null) {
        alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(), AlarmManager.INTERVAL_DAY, broadcast);
    }
}

This here is the receiver

public class AlarmReceiver extends BroadcastReceiver {
@TargetApi(Build.VERSION_CODES.JELLY_BEAN)
@Override
public void onReceive(Context context, Intent intent) {
    Intent notificationIntent = new Intent(context, TicketActivity.class);

    TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);
    stackBuilder.addParentStack(TicketActivity.class);
    stackBuilder.addNextIntent(notificationIntent);

    PendingIntent pendingIntent = stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);

    NotificationCompat.Builder builder = new NotificationCompat.Builder(context);
    SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);
    String ringer = sharedPreferences.getString("key_notifications_new_message_ringtone","");
    boolean vibrate = sharedPreferences.getBoolean("Vibrate",true);
    Uri ringtone = Uri.parse(ringer);

    Notification notification = builder.setContentTitle(context.getResources().getString(R.string.notific))
            .setContentText(context.getResources().getString(R.string.notific))
            .setTicker(context.getResources().getString(R.string.notific))
            .setSmallIcon(R.mipmap.ic_launcher)
            .setSound(ringtone)
            .setContentIntent(pendingIntent).build();

    NotificationManager notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
    if (notificationManager != null) {
        notificationManager.notify(0, notification);
    }
}}