ROME 1.6 seems to not work on Android

I recently started to use ROME and jumped directly to 1.6. Therefore, when trying to get a feed I always get the same error com.rometools.rome.io.ParsingFeedException: Invalid XML [...] Caused by: org.jdom2.JDOMException: http://apache.org/xml/features/disallow-doctype-decl feature not recognized for SAX driver org.apache.harmony.xml.ExpatReader

I used some sample codes found on the web, but all are using older versions of ROME tools. As they actually, I tried to use the same RSS feeds they use, I’ve got the same error. Note that every working example that I found used FeedFetcher.

[mishako]

@PatrickGotthard @morphet81 Do we want to realease this bugfix as version 1.6.1?

[mishako]

Thank you for the report @morphet81! I looked into it and it seems to be a bug in Rome that was introduced in 2bc58a0. The change in the order of calls to parser.setFeature and saxBuilder.setFeature is what broke the code. Can’t blame Patrick for that though, because original authors of that code did nothing to indicate that the order matters and prevent this from happening.

The fix is simple: swap around the lines 373 and 374 in WireFeedInput. Feel free to do it (preferably with a test to make sure it doesn’t happen again).

So why does the order matter? Because it’s the call to parser.setFeature that throws a SAXNotRecognizedException exception, i.e. tells us whether the feature is recognized or not. We don’t want to call saxBuilder.setFeature with an unrecognized feature, because it will silently accept it and throw a JDOMException later in SAXBuilder.build method. The problem is that at that point we’ve already lost the context and the only way to figure out what’s going on is to parse the message of the exception. We don’t want to rely on exception message though.

So basically we’re abusing parser.setFeature to find out if the feature is recognized and supported before we set it on the saxBuilder. Key word here is “before” 😃