Parsing XML in my Android App - Help Please!

[Andy Crowther]

Hi guys, new here and new to programming.  I've been using Stack Overflow, but I'm realising they aren't so tolerant with someone like myself asking lots of newbie questions, even though I've done hours of searching for my answer.

Anyway, to my issue.  I am writing an Android app that in part of it I would like to download traffic information.  I have a link to an xml file I can use - http://m.highways.gov.uk/feeds/rss/AllEvents.xml

For now though, I've downloaded this xml file and put it in my res folder.  I'll come to parsing it without downloading if we can fix the first issue

Now, at the moment I have a SAXHandler that looks like this -

public class SAXHandler extends DefaultHandler{

    private TrafficEvent newTrafficEvent;
    private String content;
    private String latitude;
    private String longitude;

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        super.startElement(uri, localName, qName, attributes);
        if(qName.equals("title")){
            newTrafficEvent = new TrafficEvent();
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        switch (qName){
            case "title":
                newTrafficEvent.title = content;
                break;
            case "road":
                newTrafficEvent.road = content;
                break;
            case "category":
                newTrafficEvent.delay = content;
                break;

            case "latitude":
                latitude = content;
                break;
            case "longitude":
                longitude = content;
                newTrafficEvent.location = new LatLng(Double.parseDouble(latitude), Double.parseDouble(longitude));
                break;
            case "description":
                newTrafficEvent.description = content;
                Traffic.trafficEvents.add(newTrafficEvent);
                break;
        }
    }

    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        content = String.copyValueOf(ch, start, length).trim();
    }
}

Then in my main activity I have -

try {
            SAXParserFactory parserFactory = SAXParserFactory.newInstance();
            SAXParser parser = parserFactory.newSAXParser();

            SAXHandler handler = new SAXHandler();
            InputSource source = new InputSource(new StringReader("allevents.xml"));
            source.setEncoding("utf-8");
            parser.parse(source, handler);
        } catch (ParserConfigurationException e) {
            e.printStackTrace();
        } catch (SAXException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

The error I get is -

org.apache.harmony.xml.ExpatParser$ParseException: At line 1, column 0: syntax error

So it looks like me first issue is my parser doesn't like the xml format?

If we can figure that, I would like to then know how to a) download this xml as the user opens the activity or b) parse it direct?

Thanks for any help you might be able to offer a struggling noob!

[Tim Moores]

A StringReader uses as its input the string used to create it. That would be "allevents.xml" rather than the contents of the file called "allevents.xml". I think you need a FileReader instead.

As to the Android-related question, please start a separate topic in the Android forum.

[Andy Crowther]

Thanks.  Makes sense.

I've made that change, I've tried moving the xml into an xml folder in Res and changed the code to be new FileReader("xml/allevents.xml") but I still get -

java.io.FileNotFoundException: xml/allevents.xml (No such file or directory)

Where should the file be?

[Tim Moores]

That's not how files are accessed in Android. Files should go into the "raw" directory, and then you would access them via something like this:

Resources res = context.getResources();
InputStream is = res.openRawResource(R.raw.allevents);

Please post any further Android-specific follow-up questions to the Android forum.

[Andy Crowther]

Awesome, thanks for the help.  I'm getting there now!