Issue with SAXparser

Question

I've implemented a SAXparser in my application which has worked fine previously but i'm having problems with a new XML document.

This is my parser

public List<Article> getLatestArticles(String feedUrl) {
URL url = null;
    try {

        SAXParserFactory spf = SAXParserFactory.newInstance();
        SAXParser sp = spf.newSAXParser();
        XMLReader xr = sp.getXMLReader();

        url = new URL(feedUrl);

        xr.setContentHandler(this);
        xr.parse(new InputSource(url.openStream()));


    } catch (IOException e) {
        Log.e("RSS Handler IO", e.getMessage() + " >> " + e.toString());
    } catch (SAXException e) {
        Log.e("RSS Handler SAX", e.toString());
    } catch (ParserConfigurationException e) {
        Log.e("RSS Handler Parser Config", e.toString());
    }
    catch (java.lang.IllegalArgumentException e){
        Log.e("RSS Handler lang", e.getMessage() + " >> " + e.toString());
    }

    return articleList;
}

The parser starts off ok but then i get a java.lang.IllegalArgumentException error. I believe this may be due to an element with no value in my xml feed, it looks like this <Description/>.

Any suggestion on how to fix this would be much appreciated.

We can help more easily if you include the stacktrace and the startElement, endElement and characters methods. — Don Roby, Sep 14 '12 at 10:58

score 1 · Accepted Answer · edited Sep 14 '12 at 15:43

If </Description> is a self closing tag (i.e. it has not opening <Description> tag and no text value) then this syntax is perfectly correct.

It is hard to tell exactly what is causing the error without seeing the callback methods (e.g. startElement method) but there is one major gottcha that you can check

The SAX parse method throws an illegalArguementException if the InputStream is null. It might be worth checking the value coming into the SAX parser.

You can use the following code to check the input stream for nulls.

InputStreamReader reader = new InputStreamReader(url.openStream());

if (!reader.ready()) {
    System.out.println("error");
}

Thanks, i found the problem in the end. It had nothing to do with the SAXparser. I'd been building a list of articles but not then transferring this to JSON as i was supposed to. This code helped me find the source of the nulls — Andy, Oct 11 '12 at 15:08

Ajay Kumar Meher · Answer 2 · 2012-09-15T11:05:35.550

0

<Description/> is the xml construction issue for SAXParser. have a look into the structure.

Ideally it should be </Description> as a closing tag.

For self-closing tags SAXParser will assume it as a closing tag.

So instead of startElement you will get a call from endElement.

edited Sep 15 '12 at 11:05

answered Sep 14 '12 at 11:10

Ajay Kumar Meher

1,932
16
24

Don Roby, Please think twice before giving negative to anybody. I am well aware of self-closing tag. The reason asking for a separate closing tag instead of self-closing is, you will get a call for endElement from the parser instead of startElement.[just check this](http://stackoverflow.com/questions/2707531/trouble-parsing-self-closing-xml-tags-using-sax-parser). – Ajay Kumar Meher Sep 15 '12 at 09:51
I rarely downvote actually. But I do tend to downvote on factual errors. I also retract them if an answer is improved. You might try including some content from the link you reference in your comment. – Don Roby Sep 15 '12 at 10:59

score 0 · Answer 3 · answered Sep 15 '12 at 07:34

The connection could close before all the data downloads. Try using a BufferedInputStream and see if that helps:

BufferedInputStream _url_ = new BufferedInputStream(new URL(feedUrl).openStream());

...

BufferedReader isr = new BufferedReader(new InputStreamReader(_url_));
InputSource is = new InputSource(isr);
xr.parse(is);

Issue with SAXparser

3 Answers3