My UI is blocked using AsyncTask with distancematrix and google Maps

Question

I\'m using google maps to show some markers. The markers are download from a database and, at the same time, I get the distancematrix from google api, between the current po

Answer 1

I'm not exactly sure what you're trying to do but I think you've made this more complicated then it has to be.

From what I understand you have a list of City objects and you use them to construct some URLs from which you retrieve a JSON object that is use to construct MarkerOptions objects.

You can do that using a AsyncTask like this:

public class Task extends AsyncTask {

    String currentLatitude;
    String currentlongitude;

    public Task(String currentLatitude, String currentlongitude){
        this.currentLatitude = currentLatitude;
        this.currentlongitude = currentlongitude;
    }

    @Override
    protected String doInBackground(City... cities) {
        final Markers mMap = ...;
        for (City city : cities) {
            GeoPoint geoPoint = city.getLocation();
            String nameBeach = city.getName();

            if (geoPoint != null) {
                String latitude = String.valueOf(geoPoint.getLatitude());
                String longitude = String.valueOf(geoPoint.getLongitude());

                HttpURLConnection urlConnection = null;
                BufferedReader reader = null;
                try {
                    URL url = new URL("https://maps.googleapis.com/maps/api/distancematrix/json?origins=" + currentLatitude + "," + currentlongitude + "&destinations=" + latitude + "," + longitude + "&key=xxx";);
                    urlConnection = (HttpURLConnection) url.openConnection();
                    reader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
                    StringBuilder result = new StringBuilder();
                    String line;
                    while ((line = reader.readLine()) != null) {
                        result.append(line);
                    }
                    JSONObject jsonObject = new JSONObject(result.toString()).getJSONArray("rows").getJSONObject(0).getJSONArray("elements").getJSONObject(0);
                    String duration = jsonObject.getJSONObject("duration").getString("text");
                    String distance = jsonObject.getJSONObject("distance").getString("text");

                    mMap.addMarker(new MarkerOptions().position(new LatLng(geoPoint.getLatitude(), geoPoint.getLongitude()))
                            .title(nameBeach)
                            .snippet(distance + ", " + duration)
                            .icon(BitmapDescriptorFactory.defaultMarker()));
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    if(reader!=null){
                        try {
                            reader.close();
                        }catch (Exception e){
                            e.printStackTrace();
                        }
                    }
                    if (urlConnection != null) {
                        try {
                            urlConnection.disconnect();
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        }

        return mMap;
    }
}

And here is how you can use this task.

public class Login extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(...);
        Task task = new Task(currentLatitude, currentlongitude){
            @Override
            protected void onPostExecute(Markers markers) {
                super.onPostExecute(markers);
                //This runs on the UI thread and "markers" is the "mMap" object that was create on the background thread.
            }
        };
        List cities = ....
        task.execute(cities.toArray(new City[cities.size()]));
    }
}

The idea is that you need to execute all the long running operation in the AsyncTask's doInBackground(...) method. Also, you don't need to create other objects to deal with the AsyncTask response, you can override the task's onPostExecute(...) inside the class you've created the task in.