Android Xml 解析空指针异常

Question

我正在尝试解析这个 xml 提要

http://www.billboard.com/rss/charts/hot-100

但每当我尝试阅读描述标签时，它都会抛出NullPointerException。文档开头有一个标签，这个标签会导致问题吗？

我能够成功提取所有其他字段。

这是我的代码：

Element element = result.getDocumentElement();
NodeList list = element.getElementsByTagName("item");
 try{           
  if(list != null && list.getLength()>0){
    for(int i=0;i<list.getLength();i++){
        Element entry = (Element)list.item(i);
        Element title = (Element)entry.getElementsByTagName("title").item(0);    
        String strTitle = title.getFirstChild().getNodeValue();
        Log.i("Zealdeveloper", "Title");
        Element link = (Element)entry.getElementsByTagName("link").item(0);
        String strLink = link.getFirstChild().getNodeValue();
        Log.i("Zealdeveloper", "Link");
        Element pubdate = (Element)entry.getElementsByTagName("pubDate").item(0);              
        String strPubdate = pubdate.getFirstChild().getNodeValue();
        Log.i("Zealdeveloper", "pubdate");
        Element description = (Element)entry.getElementsByTagName("description").item(0);              
        String strDescription = description.getFirstChild().getNodeValue();
        Log.i("Zealdeveloper", "Description"); } }

我得到的异常：

12-06 13:44:09.202: I/Zealdeveloper(824): Title
12-06 13:44:09.202: I/Zealdeveloper(824): Link
12-06 13:44:09.202: I/Zealdeveloper(824): pubdate
12-06 13:44:09.202: W/System.err(824): java.lang.NullPointerException
12-06 13:44:09.202: W/System.err(824):  at com.zealdeveloper.musicfreak.MusicFreakActivity$ParseXmlFeeds.onPostExecute(MusicFreakActivity.java:152)
12-06 13:44:09.212: W/System.err(824):  at com.zealdeveloper.musicfreak.MusicFreakActivity$ParseXmlFeeds.onPostExecute(MusicFreakActivity.java:1)
12-06 13:44:09.212: W/System.err(824):  at android.os.AsyncTask.finish(AsyncTask.java:417)
12-06 13:44:09.212: W/System.err(824):  at android.os.AsyncTask.access$300(AsyncTask.java:127)
12-06 13:44:09.212: W/System.err(824):  at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
12-06 13:44:09.212: W/System.err(824):  at android.os.Handler.dispatchMessage(Handler.java:99)
12-06 13:44:09.212: W/System.err(824):  at android.os.Looper.loop(Looper.java:123)
12-06 13:44:09.212: W/System.err(824):  at android.app.ActivityThread.main(ActivityThread.java:4627)
12-06 13:44:09.212: W/System.err(824):  at java.lang.reflect.Method.invokeNative(Native Method)
12-06 13:44:09.212: W/System.err(824):  at java.lang.reflect.Method.invoke(Method.java:521)
12-06 13:44:09.212: W/System.err(824):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
12-06 13:44:09.222: W/System.err(824):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
12-06 13:44:09.222: W/System.err(824):  at dalvik.system.NativeStart.main(Native Method)

谢谢！

Answer 1

您可以使用 RSS 提要库在此处下载 RSS 提要 JAR 文件 ----> http://code.google.com/p/superpodder/source/browse/trunk/lib/rsslib4j-0.2.jar?r=3

这样就可以解析数据了

TextView textView = (TextView) findViewById(R.id.textview);

            String feedUrl = "http://www.billboard.com/rss/charts/hot-100"; // RSS means Real Simply Syndication
            URL url = new URL(feedUrl);

            RSSHandler rsshandler = new RSSHandler();

            RSSParser.parseXmlFile(url, rsshandler, false);

            RSSChannel rssChannel = rsshandler.getRSSChannel();

            String data = rssChannel.getAboutAttribute();
            textView.append("\n\n");
            textView.append("Attributes: "+data+"\n");

            data = rssChannel.getCopyright();
            textView.append("Copyright: "+data+"\n");

            data = rssChannel.getDescription();
            textView.append("Description: "+data+"\n");

            data = rssChannel.getDocs();
            textView.append("Docs: "+data+"\n");

            data = rssChannel.getGenerator();
            textView.append("Generator: "+data+"\n");

            data = rssChannel.getLanguage();
            textView.append("Language: "+data+"\n");

            data = rssChannel.getLastBuildDate();
            textView.append("LastBuildDate: "+data+"\n");

            data = rssChannel.getLink();
            textView.append("Link: "+data+"\n");

            data = rssChannel.getPubDate();
            textView.append("PubDate: "+data+"\n");

            data = rssChannel.getTitle();
            textView.append("Title: "+data+"\n");

            data = rssChannel.getTTL();
            textView.append("TTL: "+data+"\n");

            data = rssChannel.getWebMaster();
            textView.append("WebMaster: "+data+"\n");


            RSSImage rssImage = rssChannel.getRSSImage();
            data = rssImage.getTitle();
            textView.append("ImageTitle: "+data+"\n");

            data = rssImage.getWidth();
            textView.append("ImageWidth: "+data+"\n");

            data = rssImage.getHeight();
            textView.append("ImageHeight: "+data+"\n");

            data = rssImage.getLink();
            textView.append("ImageLink: "+data+"\n");

            data = rssImage.getUrl();
            textView.append("ImageUrl: "+data+"\n");

            textView.append("\n");
            LinkedList linkedList = rssChannel.getItems();
            int size = linkedList.size();

            textView.append("Total Items: "+size+"\n");

注意：这仅适用于 rssfeed 网址，请勿使用此库解析任何其他网址

Answer 2

您的 XML 文件中是否有像“&”或“--”这样的字符？！ 我发现解析器无法解析那些！ 如果你有的话，试着改变它