Filling a spinner from JSON web data

Question

The code below is used to download a JSON data from the web and use the data to fill a spinner. I would like to know if there is better way. Is it wise to move everything from onGetPriceType to the AsyncTask?

Interface

public interface GetBuildTypeInterface {
 public void onGetBuildType(HashMap<String,String> result);
}

AsyncTask

public class GetBuildType extends AsyncTask<Void, Void, JSONArray> {
 private GetBuildTypeInterface callback;
 public GetBuildType(GetBuildTypeInterface callback) {
 this.callback = callback;
 }
 @Override
 protected JSONArray doInBackground(Void... params) {
 UserFunctions u = new UserFunctions();
 return u.getBt();
 }
 @Override
 protected void onPostExecute(JSONArray result) {
 super.onPostExecute(result);
 HashMap<String, String> map = new HashMap<String, String>();
 if (result != null) {
 map = result.parse();
 callback.onGetBuildType(map);
 } else {
 callback.onGetBuildType(null);
 }
 }
}

Activity

public class AddFillActivityApp extends ErrorActivity implements
 GetBuildTypeInterface
{
 ArrayAdapter<String> adapterBuild;
 Spinner spinBuildType;
@Override
 public void onGetPriceType(final HashMap<String, String> result) {
 if (result != null) {
 List<String> fields = new ArrayList<String>();
 fields.addAll(result.keySet());
 adapterPrice = new ArrayAdapter<String>(this,
 android.R.layout.simple_spinner_item, fields);
 adapterPrice
 .setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
 spinPriceType.setAdapter(adapterPrice);
 spinPriceType
 .setOnItemSelectedListener(new OnItemSelectedListener() {
 @Override
 public void onItemSelected(AdapterView<?> parent,
 View view, int position, long id) {
 if (position > -1) {
 String selection = spinPriceType
 .getSelectedItem().toString();
 a.setNot_priceFor(result.get(selection));
 } 
 }
 @Override
 public void onNothingSelected(AdapterView<?> arg0) { 
 }
 });
 }else error();
 }
}

Answer 1

I see a very big advantage of your current approach rather than moving the implementation of onGetPriceType to the GetBuildType class (May I suggest changing the name to GetBuildTypeTask?)

• Decoupling code . Your GetBuildType class is 100% independent of your activity. That is a good sign. If needed, you could at any time re-use the GetBuildType class and provide it with another GetBuildTypeInterface.

A side suggestion: I assume that result.parse() doesn't need to be run on the UI-thread, so you can change your class to extend AsyncTask<Void, Void, Map<String, String>> and make the conversion to map in doInBackground (or return null if u.getBt() returns null). Also, you don't need to create a new empty HashMap before parsing the JsonArray, simply Map<String, String> map = jsonArray.parse(); will do.

The only disadvantage I see with your current implementation is that you get an extra interface. But I really don't think that's so bad compared to having decoupled code.