public class ForceOfflineReceiver extends BroadcastReceiver { @Override public void onReceive(final Context context, Intent intent) { AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(context); dialogBuilder.setTitle("Warning"); dialogBuilder.setMessage("You are forced to be offline.Please try to login again."); dialogBuilder.setCancelable(false); dialogBuilder.setPositiveButton("OK", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { ActivityCollector.finishAll(); Intent intent = new Intent(context,LoginActivity.class); intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); context.startActivity(intent); } }); AlertDialog alertDialog = dialogBuilder.create(); //设置AlertDialog的类型，保证在广播接收器中可以正常弹出 alertDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT); alertDialog.show(); }}请问两处下划线的context是什么意思？FLAG_ACTIVITY_NEW_TASK的作用是什么？