今天第六章里的示例代码，运行不起来。提示没有引用的对象。

添附代码片段

 private void refreshEarthquakes() {
    // Get the XML
    URL url;
    try {
      String quakeFeed = getString(R.string.quake_feed);
      url = new URL(quakeFeed);

      URLConnection connection;
      connection = url.openConnection();

      HttpURLConnection httpConnection = (HttpURLConnection)connection;
      int responseCode = httpConnection.getResponseCode();

      if (responseCode == HttpURLConnection.HTTP_OK) {
        InputStream in = httpConnection.getInputStream();

        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();

        // Parse the earthquake feed.
        Document dom = db.parse(in);
        Element docEle = dom.getDocumentElement();

        // Clear the old earthquakes
        earthquakes.clear();

        // Get a list of each earthquake entry.
        NodeList nl = docEle.getElementsByTagName("entry");
        if (nl != null && nl.getLength() > 0) {

　　　　//这里的 i=0 被我改成了 i=1 。
          for (int i = 1 ; i < nl.getLength(); i++) {
            Element entry = (Element)nl.item(i);
            Element title = (Element)entry.getElementsByTagName("title").item(0);
            
            Element g = (Element)entry.getElementsByTagName("georss:point").item(0);
            //Element g = (Element)entry.getElementsByTagName("summary").item(0);
            
            Element when = (Element)entry.getElementsByTagName("updated").item(0);
            Element link = (Element)entry.getElementsByTagName("link").item(0);

            String details = title.getFirstChild().getNodeValue();
            String hostname = "http://earthquake.usgs.gov";
            String linkString = hostname + link.getAttribute("href");

            String point = g.getFirstChild().getNodeValue();
            String dt = when.getFirstChild().getNodeValue();
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd‘T‘hh:mm:ss‘Z‘");
            Date qdate = new GregorianCalendar(0,0,0).getTime();
            try {
              qdate = sdf.parse(dt);
            } catch (ParseException e) {
              Log.d(TAG, "Date parsing exception.", e);
            }

            String[] location = point.split(" ");
            Location l = new Location("dummyGPS");
            l.setLatitude(Double.parseDouble(location[0]));
            l.setLongitude(Double.parseDouble(location[1]));

            String magnitudeString = details.split(" ")[1];
            int end =  magnitudeString.length()-1;
            double magnitude = Double.parseDouble(magnitudeString.substring(0, end));

            details = details.split(",")[1].trim();

            Quake quake = new Quake(qdate, details, l, magnitude, linkString);

            // Process a newly found earthquake
            addNewQuake(quake);
          }
        }
      }
    } catch (MalformedURLException e) {
      Log.d(TAG, "MalformedURLException", e);
    } catch (IOException e) {
      Log.d(TAG, "IOException", e);
    } catch (ParserConfigurationException e) {
      Log.d(TAG, "Parser Configuration Exception", e);
    } catch (SAXException e) {
      Log.d(TAG, "SAX Exception", e);
    }
    finally {
    }
  }
到网页上查看时候，发现第0条地震情况无。因此就找不到了。

整个示例代码中都是如此，真是悲伤

第六章，使用Internet资源的一个问题