Question

I have a json feed from this URL which contains 20 fields and I parse all the datas..but again I need to load more data from the json feed after showing the 20 fields in listview.

I have created a AsyncTask and loaded the json in listview. this is my class

public void onCreate(Bundle savedInstanceState) {
new DoInBackgrd().execute();
}

    private class DoInBackgrd extends AsyncTask<Void, Void, Void> implements
            DialogInterface.OnCancelListener {

        private ProgressDialog processDialog;

        @Override
        protected void onPreExecute() {
            processDialog = ProgressDialog.show(List.this, "",
                    getString(R.string.loading), true);
            processDialog.setCancelable(true);
        }

        public void onCancel(DialogInterface arg0) {
            // TODO Auto-generated method stub

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

        }

        @Override
        protected Void doInBackground(Void... arg0) {
            // TODO Auto-generated method stub

            Jsonfunctions jParser = new Jsonfunctions();
            JSONObject json = jParser.getJSONFromUrl(url);
            try {
                // Getting Array of Contacts
                results = json.getJSONArray(TAG_RESULTS);

                // looping through All Contacts
                for (int i = 0; i < results.length(); i++) {
                    JSONObject c = results.getJSONObject(i);

                    id = c.getString(TAG_ID);
                    name = c.getString(TAG_NAME);
                    adress = c.getString(TAG_ADRRESS);
                    latitude = c.getString(TAG_LATITUDE);
                    latitudeAry.add(c.getString(TAG_LATITUDE).toString());
                    longitude = c.getString(TAG_lONGITUDE);
                    latitudeAry.add(c.getString(TAG_lONGITUDE).toString());
                    distance = c.getString(TAG_DISTANCE);
                    image = c.getString(TAG_IMAGE);
                    phone = c.getString(TAG_TELEPHONE);
                    telphonenumberAry
                            .add(c.getString(TAG_TELEPHONE).toString());
                    NameAry.add(c.getString(TAG_NAME).toString());

                    resourceAry.add(new ResourceClass(point, id, name, adress,
                            distance, latitude, longitude, phone));
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return null;
        }

        @Override
        protected void onPostExecute(Void unused) {
            if (processDialog.isShowing()) {
                processDialog.dismiss();
            }
            listView.setAdapter(new ASyncAdapter());
            listView.setDividerHeight(2);
            listView.setOnItemClickListener(new OnItemClickListener() {
                public void onItemClick(AdapterView<?> arg0, View arg1,
                        int position, long id) {

                    Intent details = new Intent(List.this, Details.class);
                    details.putExtra("position", position + 1);
                    details.putExtra("name", resourceAry.get(position)
                            .getName());
                    details.putExtra("adress", resourceAry.get(position)
                            .getAdress());
                    details.putExtra("phone", resourceAry.get(position)
                            .getTelephone());
                    details.putExtra("latitudes", latitude);
                    details.putExtra("longitudes", longitude);
                    startActivity(details);

                }
            });
        }
    }

Thanks in advance

Answer 1

I had just finished working on similar kind of requirement(issue faced on is specified in)

Hence I’m hoping to provide you proper solution that is helpful to you and saves ur time.

If I’m not wrong you need to populate same ListView with next 20(i.e. 21 – 40) fields obtained in response for server api.

In that case u need to call server api again and again for that u need an event. Say u add a ‘Next’ button and on its click u retrive next 20 fields(21 – 40).

Currently in ur code in ‘DoInBackgrd’, you are binding/setting Adapter(ASyncAdapter) each time you need to bind new records/fields to ListView. This is not a good practice, also it at a instance it will not refresh fields of newly assigned adapter in listView.

Hence you should :

1. Just retrieve/parse new fileds from JSon and set them in adapter. Adapter will notify your listView about data change and listView will refresh its view.

2. Considering that ‘ASyncAdapter’ is your custom adapter that implements ArrayAdapter, just add following(change Variable type from Restaurant to as per your requirement) method to it.

   public void reSet(ArrayList<Resturant> resturantsCache) {
              //This will clear your current fields/records in adpter
      clear();
   
              //This will new fields/records in adpter from provided resturantsCache ArrayList.
      for (Resturant resturant : resturantsCache) {
           add(resturant);
       }
   }
   

Hope you will be able to replace variable types in provided method and use it as per you requirements, In case you need more help please provide ASyncAdapter code.

Thanks.