Android：Intent-FLAG_ACTIVITY_NO_HISTORY无效

我有三个活动说A B C,从活动A我去B和搜索城市,从活动B我去活动c,在我保存我放入异步任务的东西
 这将保存在Activit A列表视图中,问题是在我按回按钮后保存在列表中我再次看到活动A没有保存我之前保存的名称

private class Savecity extends AsyncTask<city,String,String> {

        @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);
            if(result != null && result.equals("sucess")){

            Intent intent = new Intent(activity,cityActivity.class);
            intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
            startActivity(intent);}

        }
        @Override
        protected String doInBACkground(city... arg0) {
            try {
                ((CityPreferences) activity.getApplication()).createcity(arg0[0]);

                return "sucess";
            } catch (Exception E) {
                Log.e(tag,"",E);
                return "fail";
            }
        }

Intent i = new Intent(getBaseContext(),Activity_A.class);
i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOp);
startActivity(i);