Properly Using AsyncTask get()

Question

I am running into a problem. I need to use asynctask to retrieve JSON data and I need that data before I moved to the next part of the program. However, when using the get() method of AsyncTask I have 5 to 8 sec black screen before I see the data is displayed. I would like to display a progress dialog during the data retrieval but I cannot do this due to the black screen. Is there a way to put into another thread? here is some code

AsyncTask

public class DataResponse extends AsyncTask<String, Integer, Data> {

    AdverData delegate;
    Data datas= new Data();
    Reader reader;
    Context myContext;
    ProgressDialog dialog;
    String temp1;

public DataResponse(Context appcontext) {

    myContext=appcontext;
    }

@Override
protected void onPreExecute()
{
    dialog= new ProgressDialog(myContext);
    dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
    dialog.setCancelable(false);
    dialog.setMessage("Retrieving...");
    dialog.show(); 
};      

    @Override
    protected Data doInBackground(String... params) {
        temp1=params[0];              
        try
        {
            InputStream source = retrieveStream(temp1);
            reader = new InputStreamReader(source);
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }

            Gson gson= new Gson();
            datas= gson.fromJson(reader, Data.class);    


            return datas; 


    }


    @Override
    protected void onPostExecute(Data data) 
    {

             if(dialog.isShowing())
            {
                dialog.dismiss();
            }

    }



    private InputStream retrieveStream(String url) {

            DefaultHttpClient client = new DefaultHttpClient(); 

            HttpGet getRequest = new HttpGet(url);

            try {

               HttpResponse getResponse = client.execute(getRequest);
               final int statusCode = getResponse.getStatusLine().getStatusCode();

               if (statusCode != HttpStatus.SC_OK) { 
                  Log.w(getClass().getSimpleName(), 
                      "Error " + statusCode + " for URL " + url); 
                  return null;
               }

               HttpEntity getResponseEntity = getResponse.getEntity();
               return getResponseEntity.getContent();

            } 
            catch (IOException e) {
               getRequest.abort();
               Log.w(getClass().getSimpleName(), "Error for URL " + url, e);
            }

            return null;

         }

}

DisplayInfo

public class DisplayInfo extends Activity implements AdverData {

public static Data data;
public ProjectedData attup;
public ProjectedData attdown;
public ProjectedData sprintup;
public ProjectedData sprintdown;
public ProjectedData verizionup;
public ProjectedData veriziondown;
public ProjectedData tmobileup;
public ProjectedData tmobiledown;
public ProjectedAll transfer;
private ProgressDialog dialog;
public DataResponse dataR;

Intent myIntent; // gets the previously created intent
double x; // will return "x"
double y; // will return "y"
int spatial; // will return "spatial"


//public static Context appContext;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    StrictMode.ThreadPolicy policy = new StrictMode.
            ThreadPolicy.Builder().permitAll().build();
            StrictMode.setThreadPolicy(policy); 

    dialog= new ProgressDialog(DisplayInfo.this);
    dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
    dialog.setCancelable(false);
    dialog.setMessage("Retrieving...");
    dialog.show(); 

        myIntent= getIntent(); // gets the previously created intent
         x = myIntent.getDoubleExtra("x",0); // will return "x"
         y = myIntent.getDoubleExtra("y", 0); // will return "y"
         spatial= myIntent.getIntExtra("spatial", 0); // will return "spatial"

        String URL = "Some URL"






dataR=new DataResponse().execute(attUp).get();






@Override
public void onStart()
{more code}

Hmmm I don't see a single reference to AsyncTask in your code. Only an implementation of doInBackground(). By definition AsyncTasks will run in the background, if properly implemented and used. If your program needs to wait for the result of the AsyncTask then show a dialog while waiting. — dmon, Apr 15 '13 at 03:57
Is there a code or link you could post on that topic. I am very interested in finding out. — vaultzero, Apr 15 '13 at 04:04

score 12 · Accepted Answer · edited May 23 '17 at 12:17

12

When you are using get, using Async Task doesn't make any sense. Because get() will block the UI Thread, Thats why are facing 3 to 5 secs of blank screen as you have mentioned above.

Don't use get() instead use AsyncTask with Call Back check this AsyncTask with callback interface

edited May 23 '17 at 12:17

Community

1
1

answered Apr 15 '13 at 04:40

Pragnani

20,075
6
49
74

SO i have done what you said and setup a callback however when I use that class. it says it is null – vaultzero Apr 15 '13 at 18:24

Properly Using AsyncTask get()

1 Answers1

Linked

Related