我已经编写了一段代码来启动点击通知活动。但是如果该活动已经打开（可见），那么我想先关闭该活动，然后再打开它。请告诉我该怎么做？
这是我如何生成通知的代码：
Intent intent = new Intent(context, ViewReminders.class);
intent.putExtra("CALLER","GenNot");
intent.putExtra("ID",notification_id);
PendingIntent pIntent = PendingIntent.getActivity(context, 0, intent, 0);
NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(context);
mBuilder.setTicker("Smart Locator");
mBuilder.setSmallIcon(R.drawable.notification_icon);
mBuilder.setContentTitle(name);
DetailsContainer dc = new LocationDetails(context).getDetails(location);
mBuilder.setContentText(date +", "+dc.area+" "+dc.locality);
mBuilder.setContentIntent(pIntent).getNotification();
mBuilder.setAutoCancel(true);
mBuilder.getNotification().flags |= Notification.FLAG_AUTO_CANCEL;
Uri alarmSound = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
mBuilder.setSound(alarmSound);
NotificationManager mNotificationManager = (NotificationManager)context.getSystemService(Context.NOTIFICATION_SERVICE);
mNotificationManager.notify(document_id, notification_id, mBuilder.build());