How can I get ArrayList back to fragment from parser class after parsing data and ArrayList send to fragment to set in Recyclerview adapter?

Issue

How can I get array list back to fragment after parsing to set into RecyclerView.

I tried to do that but when I call api it run background thread, till I get ArrayList from background my fragment created and it set null array to recycler adapter.

Then, I tried this way its working but I think it is a wrong approach. Please guide me -

How can I set adapter in Fragment after parsing data and send ArrayList back to fragment and set to RecyclerView adapter?

Here is my code fragment code

  public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        setHasOptionsMenu(true);
        View view=inflater.inflate(R.layout.first_fragment,null);
        recyclerView=(RecyclerView)view.findViewById(R.id.mFirstRecyclerview);
        recyclerView.setLayoutManager(new LinearLayoutManager(this.getActivity()));
        mswipeRefreshLayout = (SwipeRefreshLayout)view.findViewById(R.id.swipelayoutm);
        ParseDataClass  mparser = new ParseDataClass(getActivity(),recyclerView,mswipeRefreshLayout);
        mparser.execute("http://192.168.8.100/fetchtext.php", "1");
        recyclerView.setOnScrollChangeListener(new View.OnScrollChangeListener() {
            @Override
            public void onScrollChange(View v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
                if (scrollX == 0) {
                    mswipeRefreshLayout.setEnabled(true);
                } else mswipeRefreshLayout.setEnabled(false);

            }
        });
        return view;
    }


    @Override
    public String toString() {
        return "FirstFragment";
    }

    @Override
    public void onPrepareOptionsMenu(Menu menu) {
            menu.findItem(R.id.rightimageitem).setVisible(false);
        super.onPrepareOptionsMenu(menu);

    }
}

And Here it is my parser class

  public ParseDataClass(Context context,RecyclerView recyclerView,SwipeRefreshLayout swipeRefreshLayout) {
        this.context = context;
        progressDialog = new ProgressDialog(this.context);
        progressDialog.setCancelable(false);
        progressDialog.setMessage("Retrieving data...");
        progressDialog.setTitle("Please wait");
        progressDialog.setIndeterminate(true);
        arrayList = new ArrayList<DataStored>();
        getArraylist = new ArrayList<DataStored>();
        this.recyclerView=recyclerView;
        this.swipeRefreshLayout=swipeRefreshLayout;

    }


    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        progressDialog.show();
    }

    private static final String TAG = "Parser";

    @Override
    protected String doInBackground(String... strings) {
        URL url = null;
        int arryLength = strings.length;
        HttpURLConnection httpURLConnection = null;

        try {
                url = new URL(strings[0]);
                String catId = strings[1];
                httpURLConnection = (HttpURLConnection) url.openConnection();
                httpURLConnection.setRequestMethod("POST");
                httpURLConnection.setDoOutput(true);
                httpURLConnection.setDoInput(true);
                OutputStream outputStream = httpURLConnection.getOutputStream();
                BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
                String post_data = URLEncoder.encode("catId", "UTF-8") + "=" + URLEncoder.encode(catId, "UTF-8");
                bufferedWriter.write(post_data);
                bufferedWriter.flush();
                bufferedWriter.close();
                outputStream.close();

            InputStream inputStream = httpURLConnection.getInputStream();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
            String result = "";
            String line = "";
            while ((line = bufferedReader.readLine()) != null) {
                result += line;
            }
            bufferedReader.close();
            inputStream.close();
            httpURLConnection.disconnect();
            return result;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }


    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);

        try {
            // RestaurantData restaurantData;
            if (s != null) {
                JSONObject jsonObject = new JSONObject(s);
                JSONArray jsonArray = jsonObject.getJSONArray("result");
                for (int i = 0; i < jsonArray.length(); i++) {
                    jsonObject = jsonArray.getJSONObject(i);
                    String branchname = jsonObject.getString("brancname");
                    String branchaddress = jsonObject.getString("branchaddres");
                    String brandname = jsonObject.getString("brandsNae");
                    String brandlogo = jsonObject.getString("brndlogo");
                    String branchlogo = jsonObject.getString("brnchlogo");
                    String discAmount = jsonObject.getString("distAmount");

                    dataStored = new DataStored(branchname, branchaddress, brandname, brandlogo, branchlogo, discAmount);
                    arrayList.add(dataStored);

                }
                myAdapter = new MyRecyclerAdapter(context, arrayList, swipeRefreshLayout);



                if (progressDialog != null && progressDialog.isShowing()) {
                    progressDialog.dismiss();
                }
                recyclerView.setAdapter(myAdapter);



            } else {
                if (progressDialog != null && progressDialog.isShowing()) {
                    progressDialog.dismiss();
                }
                ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
                if (connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState() == NetworkInfo.State.CONNECTED ||
                        connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState() == NetworkInfo.State.CONNECTED) {
                    //we are connected to a network
                    connected = true;
                } else {
                    connected = false;
                }
                if (connected == false) {
                    Toast.makeText(context, "Null Data", Toast.LENGTH_LONG).show();
                    recyclerView.setAdapter(null);
                }
            }
        } catch (JSONException e) {
            e.printStackTrace();
            Toast.makeText(context, "Error in Parsing =" + e, Toast.LENGTH_LONG).show();
            if (progressDialog != null && progressDialog.isShowing()) {
                progressDialog.dismiss();
            }
        }
    }

Now I am setting recycler view in parser class not in fragment my question is .. how can I get ArrayList back to fragment after parsing then set into recylerview adapter in fragment.

Solution

How can I set adapter in Fragment after parsing data and send ArrayList back to fragment and set to RecyclerView adapter?

Simple,

Step 1: Create an interface

public interface OnDataRetrievalCallback {
    void onDataRetrieval(ArrayList<DataStored> dataSet);
}

Step 2: Create interface instance and setter in your Parser class

public class ParseDataClass extends AsyncTask<...> {
    ....
    ...
    arrayList = new ArrayList<DataStored>();//Your arrayList to be filled
    private OnDataRetrievalCallback onDataRetrievalCallback;

    public void setOnDataRetrievalCallback(OnDataRetrievalCallback callback) {
        this.onDataRetrievalCallback = callback;
    }

    // You can send the data back to Fragment via onDataRetrievalCallback
    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);
        // After parsing and filling up the data into arrayList
        onDataRetrievalCallback.onDataRetrieval(arrayList); //arrayList to be sent
    }

}

Step 3: set DataRetrievalCallback from your Fragment

public class MyFragment extends Fragment {

    @Override
    onCreateView(.....) {
        ParseDataClass  mparser = new ParseDataClass(getActivity(),recyclerView,mswipeRefreshLayout);
        mparser.setOnDataRetrievalCallback(new OnDataRetrievalCallback{
            public void onDataRetrieval(ArrayList<DataStored> dataSet) {
                //dataSet is your arrayList, use it to set the adapter
            }
        });
        mparser.execute("http://192.168.8.100/fetchtext.php", "1");
    }
}

Answered By - Paresh P.