Question

I’m attempting to parse an rss feed, it seems to get all the nodes but none of the subelements, they all return null.

Java code:

package com.nasutek.sliceoftech;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

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

import org.w3c.dom.Document;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class RSSParser {
    private ArrayList<RSSPost> rssposts;
    private DocumentBuilderFactory factory;
    private DocumentBuilder builder;
    public RSSParser() {
        this.rssposts = new ArrayList<RSSPost>();
    }

    private String getNodeValue(NamedNodeMap map, String key) {
        String nodeValue = null;
        Node node = map.getNamedItem(key);
        if (node != null) {
            nodeValue = node.getNodeValue();
        }
        return nodeValue;
    }
    public List<RSSPost> getList() {
        return this.rssposts;
    }
    public void parse(InputStream inStream) {
        try {
            this.rssposts = new ArrayList<RSSPost>();
            this.factory = DocumentBuilderFactory.newInstance();
            this.builder = this.factory.newDocumentBuilder();
            this.builder.isValidating();
            Document doc = this.builder.parse(inStream, null);

            doc.getDocumentElement().normalize();

            NodeList itemList = doc.getElementsByTagName("item");
            final int length = itemList.getLength();

            for (int i = 0; i < length; i++) {
                final NamedNodeMap attr = itemList.item(i).getAttributes();
                final String rss_title = getNodeValue(attr, "title");
                final String rss_link = getNodeValue(attr, "link");
                final String rss_pubDate = getNodeValue(attr, "pubDate");
                final String rss_creator = getNodeValue(attr, "dc:creator");
                final String rss_sharelink = getNodeValue(attr, "guid");
                final String rss_description = getNodeValue(attr, "description");
                final String rss_content = getNodeValue(attr, "content:encoded");
                final String rss_thumbnail = itemList.item(i).getNodeName();

                RSSPost post = new RSSPost(rss_title,rss_link,rss_pubDate,rss_creator,rss_sharelink,rss_description,rss_content,rss_thumbnail);

                if (post.title != null) this.rssposts.add(post);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

RSS Feed:

<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0"
    xmlns:content="http://purl.org/rss/1.0/modules/content/"
    xmlns:wfw="http://wellformedweb.org/CommentAPI/"
    xmlns:dc="http://purl.org/dc/elements/1.1/"
    xmlns:atom="http://www.w3.org/2005/Atom"
    xmlns:sy="http://purl.org/rss/1.0/modules/syndication/"
    xmlns:slash="http://purl.org/rss/1.0/modules/slash/"
    >

<channel>
    <title>Slice of Tech &#187; Search Results  &#187;  Google</title>
    <atom:link href="http://www.sliceoftech.com/feed?s=Google" rel="self" type="application/rss+xml" />
    <link>http://www.sliceoftech.com</link>
    <description>Technology breaking news, reviews, and editorials</description>

    <lastBuildDate>Fri, 24 Jun 2011 04:43:11 +0000</lastBuildDate>
    <language>en</language>
    <sy:updatePeriod>hourly</sy:updatePeriod>
    <sy:updateFrequency>1</sy:updateFrequency>
    <generator>http://wordpress.org/?v=3.1.3</generator>
        <item>

        <title>Best Buy Joins the Music Cloud Bandwagon</title>
        <link>http://www.sliceoftech.com/2011/06/best-buy-joins-the-music-cloud-bandwagon/</link>
        <comments>http://www.sliceoftech.com/2011/06/best-buy-joins-the-music-cloud-bandwagon/#comments</comments>
        <pubDate>Wed, 22 Jun 2011 05:59:18 +0000</pubDate>
        <dc:creator>Kevin Nunez</dc:creator>
                <category><![CDATA[Cloud]]></category>

        <category><![CDATA[Best Buy]]></category>
        <category><![CDATA[Cloud computing]]></category>

        <guid isPermaLink="false">http://www.sliceoftech.com/?p=98</guid>
        <description><![CDATA[So we&#8217;ve seen cloud music storing services from Amazon, Google, and Apple &#8211; all of which work great. Best Buy, however, has decided to join the mix and come up with a cloud service themselves. They rolled out their new service called Music Cloud that lets you upload your audio to their servers and stream [...]]]></description>
            <content:encoded><![CDATA[<p style="text-align: left;"><a href="http://www.sliceoftech.com/wp-content/uploads/2011/06/Screen-Shot-2011-06-22-at-1.57.13-AM.png"><br />
<img class="aligncenter size-full wp-image-99" title="Screen Shot 2011-06-22 at 1.57.13 AM" src="http://www.sliceoftech.com/wp-content/uploads/2011/06/Screen-Shot-2011-06-22-at-1.57.13-AM.png" alt="" width="550" height="194" /></a></p>
<p style="text-align: left;">So we&#8217;ve seen cloud music storing services from Amazon, Google, and Apple &#8211; all of which work great. Best Buy, however, has decided to join the mix and come up with a cloud service themselves. They rolled out their new service called Music Cloud that lets you upload your audio to their servers and stream it from wherever you are. You can also save songs locally, and there&#8217;s apps for Android, BlackBerry, and iOS to manage and play your music. There are two versions of the service &#8211; Lite and Premium. Lite is free while premium is $3.99 per month, but Best Buy hasn&#8217;t disclosed in their official blog post what pro users will get over the free guys. Also, the service only catches songs from iTunes and not from anywhere else, so for those who avoid iTunes at all costs (don&#8217;t blame ya), you&#8217;re outta luck.</p>
<p style="text-align: left;">Why Best Buy would do this is beyond me, but I guess they thought it would be a good move to make. When it rains, it pours, and it&#8217;s certainly very &#8220;cloudy&#8221; in the tech world. Will you use Best Buy&#8217;s cloud service?</p>
<p>[via <a href="http://news.yahoo.com/s/digitaltrends/20110621/tc_digitaltrends/bestbuysoftlaunchesmusiccloudservice">Yahoo News</a>]<br />
Source: <a href="http://www.bestbuymobile.com/article/inside-best-buy-music-cloud">Best Buy Blog</a></p>
]]></content:encoded>
            <wfw:commentRss>http://www.sliceoftech.com/2011/06/best-buy-joins-the-music-cloud-bandwagon/feed/</wfw:commentRss>
        <slash:comments>0</slash:comments>

    <enclosure url="http://www.sliceoftech.com/wp-content/uploads/2011/06/Screen-Shot-2011-06-22-at-1.57.13-AM-300x105.png" length="32141" type="image/jpg" />  </item>
    </channel>
</rss>

Answer 1

It looks like you have got a bit mixed up. You have used getAttributes which returns attributes of a element, in your case the item element which has no attributes. If you had run that on the guid element you would have got one, the isPermaLink value.

This example is what allowed me to get the details of the item:

http://javamix.wordpress.com/2009/06/09/read-rss-feeds-using-jsp/

So rather than using getAttributes I used this line:

final Element element = (Element)itemList.item(i);

then to get a bit of data was this style:

final String rss_title = getElementValue(element, "title");

I was only able to run this on my pc in Eclipse as I don’t have Android available. I cannot see why it won’t work on Android though.