How in android in AlaramManger and BroadCastReceiver

Question

I want set the alarm at the specified time and implement the notification at the specified time(in a day) by using BroadcastReceiver and AlaramManager.

It alarmed specified time. After when I run the app, it again alarm even though it's not the time I set.

In other words, when I set the alarm 9:21 pm and I run the app after 9:21 pm, the notification is generated.

I just want to make the alarm notification at the specified time I set and app doesn't run. Also, when I run the app, it doesn't alarm.

How can I fix it?

This is my BroadcastReceiver Code -

public class BroadcastD extends BroadcastReceiver{
    Context context;

    @Override
    public void onReceive(Context context, Intent intent) {
        this.context = context;

        showNotification();

}

    public void showNotification() {
        NotificationManager notificationManager =
                (NotificationManager)  context.getSystemService(Context.NOTIFICATION_SERVICE);
        PendingIntent pendingIntent = PendingIntent
           .getActivity(context, 0, new Intent(context, MainActivity.class),
                    PendingIntent.FLAG_UPDATE_CURRENT);

        NotificationCompat.Builder builder = new NotificationCompat.Builder(context);
        builder.setSmallIcon(android.R.drawable.ic_dialog_alert)
            .setTicker("Ticket")
            .setContentTitle("Title")
            .setContentText("Context")
            .setWhen(System.currentTimeMillis())
            .setAutoCancel(true)
            .setContentIntent(pendingIntent);

        notificationManager.notify(1, builder.build());
    }
}

This is my MainActivity code :

public class MainActivity extends AppCompatActivity {
    AlarmManager am ;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        am = (AlarmManager) getSystemService(ALARM_SERVICE);

        AlarmHATT alarmHATT = new AlarmHATT(getApplicationContext());
        alarmHATT.Alarm();
}
 public class AlarmHATT {
    private Context context;

    public AlarmHATT(Context context) {
        this.context = context;
    }

    public void Alarm() {
        Intent intent = new Intent( context.getApplicationContext(), BroadcastD.class);
        PendingIntent sender = PendingIntent.getBroadcast(MainActivity.this, 0, intent, 0);

        Calendar calendar = Calendar.getInstance();

        calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH),
                calendar.get(Calendar.DATE), 21, 21, 0);

        am.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), 24*60*60*1000, sender);
    }
}

Answer 1

To avoid having the alarm fire immediately, configure your start time with the Calendar like this:

Calendar calendar = Calendar.getInstance();
calendar.setTimeInMillis(System.currentTimeMillis());

calendar.set(Calendar.HOUR_OF_DAY, 9);
calendar.set(Calendar.MINUTE, 30);
calendar.set(Calendar.SECOND, 0);

And then if the time you are setting has already passed today, you need to set the calendar to the following day with:

calendar.add(Calendar.DATE, 1);

That will avoid having your alarm fire immediately because it was set to a time that already passed earlier in the day.

Then continue to use calendar.getTimeInMillis() as your starting time.

Answer 2

Try below code to set alarm on a specified time.

am.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pendingIntent);