To wake up a process with the AlarmManager, you have to set the alarm first. In the Task Reminder application, the best place to do that is right after you save your task in the saveState() method in the ReminderEditActivity. Before you add that code, however, you need to add four class files to your project in the src/ folder:
<receiver android:name=“.OnAlarmReceiver” />
The leading period syntax informs Android that the receiver is in the current package — the one that is defined in the application element of the ApplicationManifest.xml file.