Alarm not working in android?

问题:

I get stuck with something that , I guess , is very trivial. Basically I am scheduling alarm for a given moment in the future :

Intent contentIntent = new Intent(this, AlarmReceiver.class); 
PendingIntent theappIntent = PendingIntent.getService(Main.this, 0,contentIntent, 0); 
Calendar calendar = Calendar.getInstance();
calendar.set(year, month, day, hour,minute); 
AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
am.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), theappIntent); 

works fine while mobile is constantly on. My problem is that alarm is not triggered after mobile is restarted and is TURNED ON on the expected time. Is there something I missed? Should I do some extra work to keep alarm scheduled after restart?

回答1:

You have to reset the alarm when device get boot. You are missing to detect the app when device boot and reset the alarm..so below is code written in manifest

<receiver android:name=".YourReceiver">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED" />
            </intent-filter>
</receiver>

<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />

Also create a BroadcastReceiver to receive the boot completed intent

 public class YourReceiver extends BroadcastReceiver {


 Context ct;

 @Override
 public void onReceive(Context context, Intent intent) 
 {
    ct=context;
    if(intent.getAction().equals("android.intent.action.BOOT_COMPLETED"))
    {
      // Reset your alarm here
      Intent contentIntent = new Intent(ct, AlarmReceiver.class); 
      PendingIntent theappIntent = PendingIntent.getService(ct, 0,contentIntent, 0); 
      Calendar calendar = Calendar.getInstance();
      calendar.set(year, month, day, hour,minute); 
      AlarmManager am = (AlarmManager) ct.getSystemService(ALARM_SERVICE);
      am.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), theappIntent); 
    }
 }

回答2:

You should add an receiver For listening android.intent.action.BOOT_COMPLETED and start your alarm from there.