Custom Adapter not working for RecyclerView in a Fragment

Question

I am working on an Android Project to display Github repo details.

I am trying to first select org name for a particular company, like Amazon has orgs on Github like AWS, AMZN, AWSLABS etc.

For this I first create a List of clickable buttons via RecyclerView(which works).

Then when user clicks on a particular org_name, the App does a HTTP request to Github to fetch relevant info and display inside a fragment which uses another RecyclerView(not working RecyclerViewRepoAdapter.java).

This part does not work as onCreateViewHolder or onBindViewHolder is not called (getItemCount is called and returns correct length)

Tried some of the suggestions mentioned like in this link! but it didn't work.

Any help is appreciated!

OrganizationInfo.java // Driver program

import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import java.util.ArrayList;
import java.util.List;

public class OrganizationInfo extends AppCompatActivity {
    private String companyName;
    private String companyAddress;
    private List<String> orgNames;
    private TextView companyNameTV;
    private TextView companyAddressTV;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_organization_info);
        getCompanyData();
        companyNameTV = findViewById(R.id.companyNameTv);
        companyAddressTV = findViewById(R.id.companyAddressTv);
        companyNameTV.setText(companyName);
        companyAddressTV.setText(companyAddress);
        initRecyclerView();

    }

    private void getCompanyData() {
        companyName = "amazon";
        companyAddress = "207 Boren Ave N, Seattle, WA 98109";
        orgNames = new ArrayList<>();
        orgNames.add("amzn");
        orgNames.add("aws");
        orgNames.add("awslabs");
    }

    private void initRecyclerView(){
//        Log.d(TAG, "initRecyclerView: init recyclerview");

        LinearLayoutManager layoutManager = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);
        RecyclerView recyclerView = findViewById(R.id.orgListRecyclerView);
        recyclerView.setLayoutManager(layoutManager);
        RecyclerViewOrgAdapter adapter = new RecyclerViewOrgAdapter(this, orgNames);
        recyclerView.setAdapter(adapter);
    }
}

GithubFragment.java

import android.os.AsyncTask;
import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.ListAdapter;
import androidx.recyclerview.widget.RecyclerView;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.List;
import java.util.Map;


/**
 * A simple {@link Fragment} subclass.
 */
public class GithubFragment extends Fragment {

    private List<Repository> repositories = new ArrayList<>();
    RecyclerView recyclerView;
    RecyclerViewRepoAdapter listAdapter;
    public GithubFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        assert getArguments() != null;
        View v =  inflater.inflate(R.layout.fragment_github, container, false);
        recyclerView = v.findViewById(R.id.repo_recycler_view);
        LinearLayoutManager layoutManager = new LinearLayoutManager(getContext());
        listAdapter = new RecyclerViewRepoAdapter(getContext(), repositories); // List of Github repos to be display

        recyclerView.setLayoutManager(layoutManager);
        recyclerView.setAdapter(listAdapter);  // Called from here after response from cloud funtion
        return v;
    }
    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        if (getArguments() != null) {
            String orgName = getArguments().getString("org_name");
            GraphQLAsyncTask graphQLAsyncTask = new GraphQLAsyncTask();
            graphQLAsyncTask.execute(orgName, "");
        }

    }

    private class GraphQLAsyncTask extends AsyncTask<String, String, String> {

        private String response;
        private Reader in;

        @Override
        protected String doInBackground(String... body) {
            Map<String, String> params = new HashMap<>();
            params.put("company", body[0]);
            params.put("language", body[1]);

            StringBuilder postData = new StringBuilder();


            try{
                for (Map.Entry param : params.entrySet()) {
                    if (postData.length() != 0) postData.append('&');
                    postData.append(URLEncoder.encode(param.getKey().toString(), "UTF-8"));
                    postData.append('=');
                    postData.append(URLEncoder.encode(String.valueOf(param.getValue()), "UTF-8"));
                }
                byte[] postDataBytes = postData.toString().getBytes("UTF-8");

                String url = "https://****************/getOrgReposGraphQL";
                URL urlObj = new URL(url);
                HttpURLConnection conn = (HttpURLConnection) urlObj.openConnection();
                conn.setDoOutput(true);
                conn.setRequestMethod("POST");
                conn.setRequestProperty("Accept-Charset", "UTF-8");
                conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
                conn.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
                conn.setReadTimeout(10000);
                conn.setConnectTimeout(15000);
                conn.getOutputStream().write(postDataBytes);

                conn.connect();
                in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
                StringBuilder sb = new StringBuilder();
                for (int c; (c = in.read()) >= 0; )
                    sb.append((char) c);
                response = sb.toString();

            } catch (ProtocolException e) {
                e.printStackTrace();
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return response;
        }


        @Override
        protected void onPostExecute(String response) {
            ParseResponse parseResponse = new ParseResponse(response);
            repositories.addAll(parseResponse.getRepositories());
            listAdapter.notifyDataSetChanged();

        }
    }
}

RecyclerViewRepoAdapter.java // Problematic Adapter

package edu.neu.madcourse.goexplore;


import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.List;

public class RecyclerViewRepoAdapter extends RecyclerView.Adapter<RecyclerViewRepoAdapter.ListViewHolder> {
    private List<Repository> mRepositories;
    private Context mContext;
    private int mCounter = 1;

    public RecyclerViewRepoAdapter(Context context, List<Repository> repos) {
        mRepositories = repos;
        mContext = context;
    }
    @NonNull
    @Override
    public ListViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_repo, parent, false);
        return new ListViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull ListViewHolder holder, int position) {
        Repository repo = mRepositories.get(position);
        holder.repoTV.setText(repo.getNameWithOwner());
        holder.repoLangugeTV.setText(repo.getPrimaryLanguage());
        holder.repoStarsTV.setText(repo.getStargazers());
        holder.repoCounter.setText(String.valueOf(mCounter++) + ".");

    }

    @Override
    public int getItemCount() {
        return mRepositories.size();
    }

    public class ListViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        TextView repoTV;
        TextView repoLangugeTV;
        TextView repoStarsTV;
        TextView repoCounter;

        public ListViewHolder(View itemView) {
            super(itemView);
            repoTV = itemView.findViewById(R.id.repo_name_row);
            repoLangugeTV = itemView.findViewById(R.id.repo_language_tv);
            repoStarsTV = itemView.findViewById(R.id.repo_stars_tv);
            repoCounter = itemView.findViewById(R.id.repo_list_number);
            itemView.setOnClickListener(this);
        }

        @Override
        public void onClick(View v) {

        }
    }
}

RecyclerViewOrgAdapter.java

import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.RecyclerView;
import java.util.List;

public class RecyclerViewOrgAdapter extends RecyclerView.Adapter<RecyclerViewOrgAdapter.ViewHolder> {
    private static final String TAG = "RecyclerViewOrgAdapter";
    private List<String> orgs;
    private Context context;

    public RecyclerViewOrgAdapter(Context context, List<String> orgs) {
        this.orgs = orgs;
        this.context = context;

    }
    @NonNull
    @Override
    public RecyclerViewOrgAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.organization_id_relative_layout, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull final RecyclerViewOrgAdapter.ViewHolder holder, final int position) {
        holder.orgIdBtn.setText(orgs.get(position));
        holder.orgIdBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                AppCompatActivity activity = (AppCompatActivity) v.getContext();
                Fragment githubFragment = new GithubFragment();
                Bundle bundle = new Bundle();
                bundle.putString("org_name", orgs.get(position));
                githubFragment.setArguments(bundle);
                activity.getSupportFragmentManager().beginTransaction().replace(R.id.github_fragment, githubFragment).addToBackStack(null).commit();
            }
        });
    }

    @Override
    public int getItemCount() {

        return orgs.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder{

        Button orgIdBtn;
        public ViewHolder(View itemView) {
            super(itemView);
            orgIdBtn = itemView.findViewById(R.id.orgIdBtn);
        }
    }



}

list_item_repo.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">
    <TextView
        android:id="@+id/repo_list_number"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="16dp"
        android:text="1."
        android:textSize="24sp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/repo_name_row"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="24dp"
        android:layout_marginTop="16dp"
        android:text="Repo Name"
        android:textSize="24sp"
        app:layout_constraintStart_toEndOf="@+id/repo_list_number"
        app:layout_constraintTop_toTopOf="parent" />
</LinearLayout>


<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">
    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="42dp"
        android:layout_height="33dp"
        android:layout_marginTop="12dp"
        app:layout_constraintStart_toStartOf="@+id/repo_name_row"
        app:layout_constraintTop_toBottomOf="@+id/repo_name_row"
        app:srcCompat="@mipmap/star_dark_round" />

    <TextView
        android:id="@+id/repo_stars_tv"
        android:layout_width="42dp"
        android:layout_height="33dp"
        android:layout_marginStart="16dp"
        android:text="1441"
        app:layout_constraintBottom_toBottomOf="@+id/imageView2"
        app:layout_constraintStart_toEndOf="@+id/imageView2"
        app:layout_constraintTop_toTopOf="@+id/imageView2" />

    <TextView
        android:id="@+id/repo_language_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="24dp"
        android:layout_marginTop="8dp"
        android:text="Ruby"
        android:textSize="18sp"
        app:layout_constraintBottom_toBottomOf="@+id/repo_stars_tv"
        app:layout_constraintStart_toEndOf="@+id/repo_stars_tv"
        app:layout_constraintTop_toTopOf="@+id/repo_stars_tv" />
</LinearLayout>
</LinearLayout>

fragment_github.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".GithubFragment">


    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/repo_recycler_view"
        android:layout_width="match_parent"
        android:orientation="vertical"
        android:layout_height="match_parent" />
</LinearLayout>

Answer 1

You are attaching adapter after getting a response from the API

LinearLayoutManager layoutManager = new LinearLayoutManager(getContext());
listAdapter = new RecyclerViewRepoAdapter(getContext(), repositories); // List of Github repos to be display

recyclerView.setLayoutManager(layoutManager);            
recyclerView.setAdapter(listAdapter);  // Called from here after response from cloud funtion

Move this code in onCreateView

assert getArguments() != null;
View v =  inflater.inflate(R.layout.fragment_github, container, false);
recyclerView = v.findViewById(R.id.repo_recycler_view);
LinearLayoutManager layoutManager = new LinearLayoutManager(getContext());
listAdapter = new RecyclerViewRepoAdapter(getContext(), repositories); // List of Github repos to be display

recyclerView.setLayoutManager(layoutManager);            
recyclerView.setAdapter(listAdapter);  // Called from here after response from cloud funtion
return v;

And after getting a response from Api in AsyncTask onPostExecute() Method add data into list and notify adapter

ParseResponse parseResponse = new ParseResponse(response);
repositories = parseResponse.getRepositories();
listAdapter.notifyDataSetChanged();