java.lang.IllegalArgumentException: Unsupported element: rss

Question

I am trying to 'GET' a rss feed.

 public RssFeed(String url) {
    _url = url;
    String res = this.api.get(url);
    ByteArrayInputStream bis = new ByteArrayInputStream(res.getBytes());

    try {
        bis.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

    XMLDecoder decoder = new XMLDecoder(bis);
    try {
        Object xml = decoder.readObject();
        _response = xml.toString();
    } catch(Exception e) {
        e.printStackTrace();
    } finally {
        decoder.close();
    }
}

When I check what's inside of 'res'. It appears to get this entire XML. But then, I am trying to decode it and I get:

java.lang.IllegalArgumentException: Unsupported element: rss

Can someone help me with that? I am new to Java.

Thanks!

Answer 1

XMLDecoder is meant to be used on elements created by XMLEncoder. Since you're scraping this XML from the web, the elements in this XML may not be valid according to these classes. Use a more generic XML parser, such as DocumentBuilder::parse() to handle this.

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();

try {
    builder.parse(url);
} catch (IOException e) {
    e.printStackTrace();
} catch (SAXParseException e) {
    e.printStackTrace();
} catch (IllegalArgumentException e) {
    e.printStackTrace();
}