在if / else语句中调用AsyncTask吗？-Android

Question

So, I made a function to return an ArrayList of strings. In that function, i have an if/else statement. In the if statement I start a background thread using AsyncTask. My question is, will my function return me the ArrayList called queriedCardIDList before I finish the AsyncTask? And if so, how do I work around this?

Cheers!

public ArrayList<String> getCardIDList()
{
   if(shouldIQuery())
   {
      QueryCardsAsyncTask queryCardsAsyncTask = new QueryCardsAsyncTask();
      queryCardsAsyncTask.execute();
   }
   else
   {
      myPreferences.loadCardsPrefs();
      for(CardModel c : myPreferences.getSavedCards())
      {
         queriedCardIDList.add(c.getCardID());
      }
      return queriedCardIDList;
   }
   return queriedCardIDList; 
}

Answer 1

Manage your async task as mentioned below,

public class QueryCardsAsyncTask extends AsyncTask<Void, Void, ArrayList<String>> {

    private ArrayList<String> queriedCardIDList = new ArrayList<>();

    @Override
    protected ArrayList<String> doInBackground(Void... params) {
        if (shouldIQuery()) {
            // You logic to be written in async task
        } else {
            // else part, get your data from preference

            myPreferences.loadCardsPrefs();
            for (CardModel c : myPreferences.getSavedCards()) {
                queriedCardIDList.add(c.getCardID());
            }
        }

        return queriedCardIDList;
    }

    @Override
    protected void onPostExecute(ArrayList<String> cardIdList) {
        super.onPostExecute(cardIdList);
        // Now use cardIdList here as per your requirement
    }
}

Then just call async task only

 QueryCardsAsyncTask queryCardsAsyncTask = new QueryCardsAsyncTask();
 queryCardsAsyncTask.execute();