警报管理器不起作用

Question

Alarm manager in my app does not work. I do everything like described here https://developer.android.com/training/scheduling/alarms.html but the alarm does not work.
Here is my code:

manifest

    <uses-permission android:name="com.android.alarm.permission.SET_ALARM"/>

Reciever (Reciever registered in the Manifest)

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

    Intent alarmIntent = new Intent(Constants.ALARM_INTENT);
    alarmIntent.setClass(context, NotificationActivity.class);
    alarmIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    context.startActivity(alarmIntent);
}

Activity

AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(context, AlarmReceiver.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intent, 0);

Calendar calendar = Calendar.getInstance();
calendar.setTimeInMillis(System.currentTimeMillis());
calendar.set(Calendar.HOUR_OF_DAY, 1);
calendar.set(Calendar.MINUTE, 30);

alarmManager.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP,
        calendar.getTimeInMillis(), AlarmManager.INTERVAL_DAY, pendingIntent);

I do not know how to make it work. Please, help me to fix it.

Answer 1

First, remove the SET_ALARM permission, as it is not relevant here.

Second, you need to ensure that your Calendar object is in the future. Most of the time, yours will be in the past, because you are using calendar.set(Calendar.HOUR_OF_DAY, 1) and set(Calendar.MINUTE, 30) . If you execute this code after 01:30, it will be in the past. In that case, you need to add() one day to make it be tomorrow at 01:30.

Third, use adb shell dumpsys alarm to see if your alarm is scheduled, once you make the above fixes.

Fourth, use LogCat to see if there are any warnings or errors coming from your code, such as perhaps AlarmReceiver or NotificationActivity not being registered in the manifest.

Answer 2

You're asking for an alarm based on the system's elapsed realtime clock here:

alarmManager.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP,
        calendar.getTimeInMillis(), AlarmManager.INTERVAL_DAY, pendingIntent);

But you're passing it a time based on a normal calendar clock. If you want an alarm to happen using a calendar-based clock, say this instead:

alarmManager.setRepeating(AlarmManager.RTC_WAKEUP,
        calendar.getTimeInMillis(), AlarmManager.INTERVAL_DAY, pendingIntent);

Note the differnce in javadoc between ELAPSED_REALTIME_WAKEUP and RTC_WAKEUP .