Fragment not getting loaded in main frame. on api call through retrofit in Android

Question

This is one of my fragment I am using in the navigation drawer. I populating the data from api and displaying in recyclerview. I have checked in the log and it displays the data in log but data is not getting populated in recycler view. I tried with breakpoints and logs. The data is coming in arraylist and I also tried with static data which is getting displayed. I am not able to understand where I am missing. And due to this fragment the other fragments are also not getting loaded in main frame. It appears blank. Thanks in advance.

public class HomeFragment extends Fragment {

private Context mContext;
private RecyclerView rvMain;
ArrayList<DataModel> arrayList;
private ProgressBar pb;
private ApiInterface apiInterface;

public HomeFragment(Context mContext) {
    this.mContext = mContext;
}

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    return inflater.inflate(R.layout.fragment_main, container, false);
}

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    Log.d("Fragment", "onViewCreated: ");
    rvMain = view.findViewById(R.id.main_category_rv);
    pb = view.findViewById(R.id.main_pb);
    arrayList = new ArrayList<>();

    prepareData();
    pb.setVisibility(View.GONE);
}

private void prepareData() {
    pb.setVisibility(View.VISIBLE);
    apiInterface = ApiRequest.createService(ApiInterface.class);

    Call<MainCategoryModel> call = apiInterface.readJson();

    call.enqueue(new Callback<MainCategoryModel>() {
        @Override
        public void onResponse(Call<MainCategoryModel> call, Response<MainCategoryModel> response) {
            if (response.isSuccessful()) {
                for (int i = 0; i < response.body().getData().getCategory().size(); i++) {
                    arrayList.add(new DataModel(response.body().getData().getCategory().get(i).getTitle(), response.body().getData().getCategory().get(i).getImage()));
                }
            } else {
                Log.d("Response", "onResponse: " + response.errorBody());
            }
        }

        @Override
        public void onFailure(Call<MainCategoryModel> call, Throwable t) {

        }
    });
    DataAdapter adapter = new DataAdapter(mContext, arrayList, new DataAdapter.RecyclerViewClickListener() {
        @Override
        public void onClick(View view, int position) {

        }
    });
    rvMain.setAdapter(adapter);

    AutoFitGridLayoutManager layoutManager = new AutoFitGridLayoutManager(mContext, 500);
    rvMain.setLayoutManager(layoutManager);
  }
}

Answer 1

First, make your adapter global in that activity, outside any method

DataAdapter adapter;

then you need to notify your adapter that you have added data with

yourAdapter.notifyDataSetChanged();

your prepareData method should be like this

private void prepareData() {
    pb.setVisibility(View.VISIBLE);
    apiInterface = ApiRequest.createService(ApiInterface.class);

    adapter = new DataAdapter(mContext, arrayList, new DataAdapter.RecyclerViewClickListener() {
        @Override
        public void onClick(View view, int position) {

        }
    });

    AutoFitGridLayoutManager layoutManager = new AutoFitGridLayoutManager(mContext, 500);

    Call<MainCategoryModel> call = apiInterface.readJson();

    call.enqueue(new Callback<MainCategoryModel>() {
        @Override
        public void onResponse(Call<MainCategoryModel> call, Response<MainCategoryModel> response) {
            if (response.isSuccessful()) {
                for (int i = 0; i < response.body().getData().getCategory().size(); i++) {
                    arrayList.add(new DataModel(response.body().getData().getCategory().get(i).getTitle(), response.body().getData().getCategory().get(i).getImage()));
                }
                adapter.notifyDataSetChanged(); // notify your adapter here
            } else {
                Log.d("Response", "onResponse: " + response.errorBody());
            }
        }

        @Override
        public void onFailure(Call<MainCategoryModel> call, Throwable t) {

        }
    });
    rvMain.setAdapter(adapter);
    rvMain.setLayoutManager(layoutManager);
  }
}

why static data show you the list, because its sync, but retrofit enqueue is using async call, it may need few time to get the data