My app screen goes blank while fetching data

Question

My App retrieves data from gaurdian news api and shows it in the form of list and used an customer Array Adapter. Whenever I run, the app shows nothing but goes blank. There are no errors during build or run. I can't find where am I going wrong.

Please help...

MainActivity class

package com.example.newsapp;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
    private final String url = "https://content.guardianapis.com/search?api-key=98c2fc67-0080-4f70-a3b7-fe216828b82d";
    private ListView mListView;
    private ArrayList<News> news;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        news = new ArrayList<>();
        mListView = findViewById(R.id.list);
        NewsAdapter adapter = new NewsAdapter(this, news);
        mListView.setAdapter(adapter);
        RequestQueue queue = Volley.newRequestQueue(this);
        JsonObjectRequest jsonObjectRequest;
        jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, url, null, new Response.Listener<JSONObject>() {
            @Override
            public void onResponse(JSONObject response) {
                try {
                    JSONObject rootResponses = response.getJSONObject("response");
                    JSONArray results = rootResponses.getJSONArray("results");
                    for(int i = 0; i<results.length(); i++){
                        JSONObject newsRoot = results.getJSONObject(i);
                        String title = newsRoot.getString("webTitle");
                        String category = newsRoot.getString("sectionName");
                        String date = newsRoot.getString("webPublicationDate");
                        News newsObj = new News(title, category, date);
                        news.add(newsObj);
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Log.e("TAG", "Error" + error );
            }
        });
        queue.add(jsonObjectRequest);
    }
}

Answer 1

You need to notify the NewsAdapter when items have been added to it. Otherwise it won't know to redraw. Assuming NewsAdapter is a RecyclerViewAdapter, call newsAdapter.notifyDataSetChanged() at the end of onResponse.