title: Attempt to invoke virtual method 'java.lang.String' on a null object reference when extracting data using from an arraylist
body: <p>I am new to this platform and i've been stuck at this error for sometime i've searched for this error online but non of the answers seem to satisfy my case. I am trying to extract data using XmlPullparser on Android and adding the extracted data to an arraylist of type model('model' object that i defined). The XmlPullparser is parsing the document correctly as i tried to store the data in an arraylist of type String and it worked. The issue comes about when i store to the former and the following error arises</p>
  
  <pre><code>  java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.example.newsmodel.model.getTitles()' on a null object reference
          at com.example.newsmodel.MainActivity$GetStoriesInBackground.onPostExecute(MainActivity.java:121)
          at com.example.newsmodel.MainActivity$GetStoriesInBackground.onPostExecute(MainActivity.java:49)
          at android.os.AsyncTask.finish(AsyncTask.java:755)
          at android.os.AsyncTask.access$900(AsyncTask.java:192)
          at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:772)
          at android.os.Handler.dispatchMessage(Handler.java:107)
  </code></pre>
  
  <p>Here's the code for parsing the Xml document:</p>
  
  <pre><code>
  import androidx.appcompat.app.AppCompatActivity;
  
  import android.annotation.SuppressLint;
  import android.content.Context;
  import android.net.ConnectivityManager;
  import android.net.NetworkInfo;
  import android.os.AsyncTask;
  import android.os.Bundle;
  import android.widget.TextView;
  
  import org.xmlpull.v1.XmlPullParser;
  import org.xmlpull.v1.XmlPullParserException;
  import org.xmlpull.v1.XmlPullParserFactory;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.util.ArrayList;
  
  public class MainActivity extends AppCompatActivity {
      TextView tvtitle;
      TextView tvDescription;
      ArrayList&lt;String&gt; titles;
      ArrayList&lt;String&gt; descriptions;
      ArrayList&lt;model&gt; items;
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
          tvtitle = (TextView) findViewById(R.id.tvTitle);
          tvDescription = (TextView) findViewById(R.id.tvDescription);
          titles = new ArrayList&lt;&gt;();
          descriptions = new ArrayList&lt;&gt;();
          items = new ArrayList&lt;model&gt;();
          new GetStoriesInBackground().execute();
      }
      private InputStream getInputStream(URL url) {
          try {
              return url.openConnection().getInputStream();
          } catch (IOException e) {
              return null;
          }
      }
  
  
      @SuppressLint("StaticFieldLeak")
      public class GetStoriesInBackground extends AsyncTask&lt;Void, Void, String&gt;
      {
  
          @Override
          protected String doInBackground(Void... params) {
  
              try {
  
                  URL url = new URL("https://www.businessdailyafrica.com/539444-539444-view-asFeed-bfdflfz/index.xml");
  
                  XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
                  factory.setNamespaceAware(false);
                  XmlPullParser xpp = factory.newPullParser();
  
                  // get the XML from an input stream
                  xpp.setInput(getInputStream(url), "UTF_8");
  
                  //variable to check if parser is inside &lt;item&gt; tag
                  boolean insideItem = false;
  
                  // Returns the type of current event: START_TAG, END_TAG, etc..
                  int eventType = xpp.getEventType();
                  model item = null;
                  while (eventType != XmlPullParser.END_DOCUMENT) {
                      if (eventType == XmlPullParser.START_TAG) {
  
                          if (xpp.getName().equalsIgnoreCase("item")) {
                              insideItem = true;
                              item = new model();
                          } else if (xpp.getName().equalsIgnoreCase("title")) {
                              if (insideItem)
                                  //titles.add(xpp.nextText()); //extract the headline
                                  item.setTitles(xpp.nextText());
                          }
                          else if (xpp.getName().equalsIgnoreCase("description")) {
                              if (insideItem)
                                  //descriptions.add(xpp.nextText());//extract the link of article
                                 item.setDescriptions(xpp.nextText());
                            //add item to the arraylist after the last required tag has been extracted
                                  items.add(item);
                          }
                      }else if(eventType==XmlPullParser.END_TAG &amp;&amp; xpp.getName().equalsIgnoreCase("item")){
                          insideItem=false;
                      }
  
                      eventType = xpp.next(); //move to next element
                  }
  
              } catch (MalformedURLException e) {
                  e.printStackTrace();
              } catch (XmlPullParserException e) {
                  e.printStackTrace();
              } catch (IOException e) {
                  e.printStackTrace();
              }
  
              return null;
  
          }
  
  
          @Override
          protected void onPostExecute(String result) {
            //  tvtitle.setText(titles.get(1));
            //  tvDescription.setText(descriptions.get(1));
              tvtitle.setText(items.get(0).getTitles());
              tvDescription.setText(items.get(0).getDescriptions());
  
          }
  
      }
  }
  </code></pre>
  
  <p>the object class:</p>
  
  <pre><code>public class model {
      public String titles;
      public String descriptions;
  
      public String getTitles() {
          return titles;
      }
  
      public void setTitles(String titles) {
          this.titles = titles;
      }
  
      public String getDescriptions() {
          return descriptions;
      }
  
      public void setDescriptions(String descriptions) {
          this.descriptions = descriptions;
      }
  }
  </code></pre>
  
  <p>Proof that the parser is extracting the data while using descriptions/titles Arraylist:
  <a href="https://i.stack.imgur.com/n7943.png" rel="nofollow noreferrer">emulator screenshot with text extracted from xml</a></p>