Basic RSS Reader in Java

Part of my effort to teach myself code is to write programs that I can actually use. Since Google Reader will self-destruct in less than a month, I’ve been looking at how to roll my own RSS Reader.

I found this code at Tully Rankin’s Website. It threw a couple of errors, and I spent the evening squashing the bugs, but in the end, I got it to work. The next step will be taking this and reworking it into something in Objective-C.

Here is the code:

        import java.net.URL;
        import javax.xml.parsers.DocumentBuilder;
        import javax.xml.parsers.DocumentBuilderFactory;
        import org.w3c.dom.Document;
        import org.w3c.dom.Element;
        import org.w3c.dom.Node;
        import org.w3c.dom.NodeList;
        import java.util.Scanner;  //ended up not being used
        import java.io.InputStream;

        /*
         * Basic RSS Reader, 2013-05-26
         * based on Java RSS Reader Example by Tully Rankin
         * http://www.tullyrankin.com/java-rss-reader-example
         */

        public class RSSReader {

            /*
             * This ended up not being needed, but I might want it in the
             * future.
             * Code pulled from:
             * http://stackoverflow.com/questions/309424/read-convert-an-inputstream-to-a-string
             */
            public static String convertStreamToString(InputStream is) {
                Scanner s = new Scanner(is, "UTF-8").useDelimiter("\\A");
                return s.hasNext() ? s.next() : "";
            }

            private static RSSReader instance = null;

            private URL rssURL;

            private RSSReader () {}

            public static RSSReader getInstance() {
                if (instance == null)
                    instance = new RSSReader();
                return instance;
            }

            public void setURL(URL url) {
                rssURL = url;
            }

            /*
             * Here is where the wicket got sticky.
             * The original line opened the rssURL stream and parsed it in the
             * same line, which generated an unexpected end of file error. The
             * solution was to open the input stream first and then parse it.
             * 
             * Also, Tully's code referred to specific headers in his XML file.
             * I modified this to refer to the DF XML file.
             */
            public void writeFeed() {
                try {
                    DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
                    //Document doc = builder.parse(rssURL.openStream());
                    InputStream is = rssURL.openStream();
                    //String holder = convertStreamToString(is);
                    //System.out.println(holder);
                    Document doc = builder.parse(is);

                    NodeList items = doc.getElementsByTagName("entry");

                    for (int i = 0; i < items.getLength(); i++) {
                        Element item = (Element)items.item(i);
                        System.out.println(getValue(item, "title"));
                        System.out.println(getValue(item, "content"));
                        //System.out.println(getValue(item, "link"));
                        System.out.println();
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

            public String getValue(Element parent, String nodeName) {
                return parent.getElementsByTagName(nodeName).item(0).getFirstChild().getNodeValue();
            }

            public static void main(String[] args) {
                try {
                    RSSReader reader = RSSReader.getInstance();
                    reader.setURL(new URL("http://dorky.radiofreepirate.org/feeds/posts/default"));
                    reader.writeFeed();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }