How do you start an Activity with AlarmManager in Android?

Question

I\'ve poured through a dozen tutorials and forum answers about this problem, but still haven\'t been able to get some working code together. I\'ll try to keep the question s

Answer 1

In my experience you can achieve this without broadcast receiver, just use PendingIntent.getActivity() instead of getbroadcast()

private void setReminder(){

AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
            Calendar startTime = Calendar.getInstance();
            startTime.add(Calendar.MINUTE, 1);
            Intent intent = new Intent(ReminderActivity.this, ReminderActivity.class);
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            PendingIntent pendingIntent = PendingIntent.getActivity(ReminderActivity.this, 1, intent, PendingIntent.FLAG_UPDATE_CURRENT);
            alarmManager.set(AlarmManager.RTC, startTime.getTimeInMillis(), pendingIntent);   
}

I've tested this code on android O but I'm not sure about other android versions please inform me if this doesn't work on any other android version.

Answer 2

add this in your android mainifest file and it will hopefully work

<activity android:name=".MyReceiver" />
        <receiver android:name=".MyReceiver"> </receiver>

Answer 3

I had this problem too long ago to know which answer is correct, but thank you to everyone for their responses. I'm self-answering so the question isn't still open.

Answer 4

Main Problem : if you close completely you're app and expect to start you're activity after 3 seconds, you wrong. because when you close you're app , you're app cant receive broadcast, for solve this problem use services instead of broadcasts.

Point: when you're service would ran ,you cant start your activity if your app wouldn't in foreground.

Solution: I think when your service started you can again set Alarmmanager to start your activity with PendingIntent for just now.

Remember :

1. When you create your intent for pass it to pendingIntent add the FLAG_ACTIVITY_NEW_TASK to it.
2. For this PendingIntent use PendingIntent.getActivity() method and for the first PendingIntent use PendingIntent.getService() method.

I hope this help you.

Answer 5

In case someone else stumbles upon this - here's some working code (Tested on 2.3.3 emulator):

public final void setAlarm(int seconds) {
    // create the pending intent
    Intent intent = new Intent(MainActivity.this, AlarmReceiver.class);
    // intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    pendingIntent = PendingIntent.getBroadcast(MainActivity.this, 0,
            intent, 0);
    // get the alarm manager, and scedule an alarm that calls the receiver
    ((AlarmManager) getSystemService(ALARM_SERVICE)).set(
            AlarmManager.RTC, System.currentTimeMillis() + seconds
                    * 1000, pendingIntent);
    Toast.makeText(MainActivity.this, "Timer set to " + seconds + " seconds.",
            Toast.LENGTH_SHORT).show();
}

public static class AlarmReceiver extends BroadcastReceiver {
    public void onReceive(Context context, Intent intent) {
        Log.d("-", "Receiver3");
    }
}

AndroidManifest.xml:

    <receiver android:name="com.example.test.MainActivity$AlarmReceiver" >
    </receiver>

Issues with BenLambell's code :

• EITHER:
  • Move the receiver to it's own .java file or
  • make the inner class static - so it can be accessed from outside
• Receiver is not declared correctly in the manifest:
  • if it's an inner class in MainActivity use: <receiver android:name="package.name.MainActivity$AlarmReceiver" ></receiver>
  • if it's in a separate file: <receiver android:name="package.name.AlarmReceiver" ></receiver>

If your intention is to display a dialog in the receiver's onReceive (like me): that's not allowed - only activities can start dialogs. This can be achieved with a dialog activity.

You can directly call an activity with the AlarmManager:

Intent intent = new Intent(MainActivity.this, TriggeredActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(MainActivity.this, 0, intent, PendingIntent.FLAG_ONE_SHOT);
((AlarmManager) getSystemService(ALARM_SERVICE)).set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + seconds * 1000, pendingIntent);

Answer 6

According to Java convention class name begin with Capital letter.So change your

"myReceiver" to "MyReceiver" and  "myActivity" to "MyActivity".

Then add your receiver in the manifest file like the below.

<application 
------------
<receiver android:name="MyReceiver"></receiver>
---------------------
</application>