Question

I currently have a class UserFunctions that does all my user actions e.g. register, login etc. In the UserFunctions class there’s a JSONParser object that does all the actual HTTP calls and returns the JSONObject.

public class UserFunctions {

    private JSONParser jsonParser;

    private static String registerURL = Constants.registerUrl;

    // constructor
    public UserFunctions(){
        jsonParser = new JSONParser();
    }

    public JSONObject register(){
        // getting JSON Object
        JSONObject json = jsonParser.getJSONFromUrl(registerURL);
        // return json
        return json;
    }
...
}

and then in my event handler of my activity classes I just do UserFunctions.register().

My question is, I now want to do all these calls in a background thread and at the same time show a ProgressDialog. I know running in the background thread is achieved with the AsyncTask.

But how should I achieve this design such that I can still do UserFunctions.register() in my Activity class, everything to be done in a background thread and a progressDialog shown.

Answer 1

Ok for this there are two parts the progress dialog and the async task, you need to move your JSONparser into the actual async task. If you want to use multiple progress dialogs just call them before calling the asynctask and close them when it returns

private class JsonRetriever extends AsyncTask<Url, Void, JSONObject>{
            private JSONParser jsonParser;
            private ProgressDialog dialog;

    public JsonRetriever(Context c){
        dialog= new ProgressDialog(c);
        jsonParser= new JSONParser();
    }
    protected void onPreExecute() {
          dialog.setMessage("Starting retrieval");
          dialog.show();
    }
    protected JSONObject doInBackground(Url... params) {
         try{
            return jsonParser.getJSONFromUrl(params[0]);
        }catch(Exception e){
            return false;
        }
        return true;
    }
    protected void onPostExecute(final JSONObject success) {
             if (dialog.isShowing()) {
                     dialog.dismiss();
            }
      }
}

Then to call this just do

public JSONObject register(){
    return new JSONRetriever(this).execute(registerURL).get();
}