// Hashmap for ListView
ArrayList<HashMap<String, String>> all_itemList;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_helloballi);

    all_itemList = new ArrayList<HashMap<String, String>>();
    // Calling async task to get json
    new getAllItem().execute();
}


private class getAllItem extends AsyncTask<Void, Void, Void> {


    @Override
    protected Void doInBackground(Void... arg0) {
        // Creating service handler class instance
        ServiceHandler sh = new ServiceHandler();

        // Making a request to url and getting response
        String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);

        Log.d("Response: ", "> " + jsonStr);

        if (jsonStr != null) {
            try {

                all_item = new JSONArray(jsonStr);


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

                        String item_id = c.getString(TAG_ITEM_ID);
                        String category_name = c.getString(TAG_CATEGORY_NAME);
                        String item_name = c.getString(TAG_ITEM_NAME);

                        // tmp hashmap for single contact
                        HashMap<String, String> allItem = new HashMap<String, String>();

                        // adding each child node to HashMap key => value
                        allItem.put(TAG_ITEM_ID, item_id);
                        allItem.put(TAG_CATEGORY_NAME, category_name);
                        allItem.put(TAG_ITEM_NAME, item_name);

                        // adding contact to contact list
                        all_itemList.add(allItem);

                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
        } else {
            Log.e("ServiceHandler", "Couldn't get any data from the url");
        }

        return null;
    }
}