Classloading in Rome

As a side-project at work, I’ve been working on an ant task to generate an atom feed of something. The something’s not really important.

Rather than re-invent the wheel, I did a quick search on google for a Java library to take care of the feed processing for me. Sure enough, Rome seemed to fit the bill.

Merrily testing away in my Eclipse workbench, I quickly wrote the code to generate my atom feed. All was good with the world. The planets may or may not have aligned. And then I came to run it through ant.

Unfortunately, that’s where the problems started…

BUILD FAILED
C:\testAnt.xml:6: java.lang.ExceptionInInitializerError
 at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:115)
 at org.apache.tools.ant.Task.perform(Task.java:348)
...
Caused by: java.lang.ExceptionInInitializerError
 at java.lang.J9VMInternals.initialize(J9VMInternals.java:222)
 at com.sun.syndication.io.SyndFeedInput.build(SyndFeedInput.java:110)
...
Caused by: java.lang.NullPointerException
 at java.util.Properties.load(Properties.java:267)
 at com.sun.syndication.io.impl.PropertiesLoader.<init>(PropertiesLoader.java:74)
 at com.sun.syndication.io.impl.PropertiesLoader.getPropertiesLoader(PropertiesLoader.java:46)
 at com.sun.syndication.io.impl.PluginManager.<init>(PluginManager.java:54)
 at com.sun.syndication.io.impl.PluginManager.<init>(PluginManager.java:46)
 at com.sun.syndication.feed.synd.impl.Converters.<init>(Converters.java:40)
 at com.sun.syndication.feed.synd.SyndFeedImpl.<clinit>(SyndFeedImpl.java:59)

Bugger.

A quick google only turns up 2 useful hits: here and here. Both links seem to suggest that Rome can run into problems with the way it loads its classes. After much hacking around, I found that a (somewhat hacky) way to solve this was by over-riding the Thread’s ClassLoader in my main class; e.g.

public class Test extends Task{

    public void execute(){

        ClassLoader cl = Test.class.getClassLoader();
        Thread.currentThread().setClassLoader(cl);

        // now do Rome stuff
        ...
    }
}

It’s not pretty, but it works. For now.