android.os.NetworkOnMainThreadException for Chapter 6 Earthquake Example in Professional Android 4 Application Development

Question

Like a lot of people I've encountered the NetworkOnMainThreadException when attempting to use the Chapter 6 Earthquake example. I typed the code in from the book (see below) which I believe should remove this problem because the network activity is not occurring on the UI thread anymore.

So can anyone see what I may have done wrong here? I realise that a better solution would be to use different code entirely such as AsyncTasks or Services but I'm really wondering what is wrong with the code as it stands?

In case its relevant, my manifest has the min SDK as 11 and the target SDK as 19.

package com.example.earthquake;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.GregorianCalendar;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

import android.app.ListFragment;
import android.location.Location;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.widget.ArrayAdapter;

public class EarthquakeListFragment extends ListFragment {

    ArrayAdapter<Quake> aa;
    ArrayList<Quake> earthquakes = new ArrayList<Quake>();

    private static final String TAG = "EARTHQUAKE";
    private Handler handler = new Handler();

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        int layoutId = android.R.layout.simple_list_item_1;
        aa = new ArrayAdapter<Quake>(getActivity(), layoutId, earthquakes);
        setListAdapter(aa);

        Thread t = new Thread(new Runnable() {
            public void run() {
                refreshEarthquakes();
            }
        });
        t.run();
    }

    public void refreshEarthquakes() {
        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();

                Document dom = db.parse(in);
                Element docEle = dom.getDocumentElement();

                earthquakes.clear();

                NodeList nl = docEle.getElementsByTagName("entry");
                if (nl != null && nl.getLength() > 0) {
                    for (int i = 0; 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 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();

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

                        handler.post(new Runnable() {
                            @Override
                            public void run() {
                                addNewQuake(quake);
                            }
                        });
                    }
                }
            } 
        } catch (MalformedURLException e) {
            Log.d(TAG, "MalformedURLException");
        } catch (IOException e) {
            Log.d(TAG, "IOException");
        } catch (ParserConfigurationException e) {
            Log.d(TAG, "ParserConfigurationException");
        } catch (SAXException e) {
            Log.d(TAG, "SAXException");
        } finally {
        }
    }

    private void addNewQuake(Quake _quake) {
        earthquakes.add(_quake);
        aa.notifyDataSetChanged();
    }
}

Answer 1

Change this

t.run();

to

t.start();

Check this

http://developer.android.com/reference/java/lang/Thread.html