我收到的通知非常有效。这些通知由服务创建。当我试图取消通知时，用户有3分钟没有点击它。我试过卡拉库里的方法https://stackoverflow.com/a/23874764，但什么也没发生。警报不工作，广播接收器未被调用。
服务类中的报警管理器：

notificationManager.notify(notificationId, n);
//set up alarm
AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
Intent intent = new Intent(context, MyReceiver.class);                                        intent.setAction("com.example.example.action.CANCEL_NOTIFICATION");
intent.putExtra("notification_id", notificationId);
PendingIntent pi = PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
alarmManager.set(AlarmManager.RTC_WAKEUP,180000,pi);

广播接收器 onReceive 方法：

public void onReceive(Context context, Intent intent) {
// do something
final String action = intent.getAction();
Log.d("Reciver","onReceive lunched");
if ("com.example.example.action.CANCEL_NOTIFICATION".equals(action)) {
int id = intent.getIntExtra("notification_id", -1);
if (id != -1) {
NotificationManager notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
notificationManager.cancel(id);
Log.d("Noti "+id," canceled ");
}}}

我以前没和报警经理打过交道。我想知道原因，但没找到，希望有人能帮我