Some Java libraries specify interface implementations through the Service Provider Interface (http://docs.oracle.com/javase/tutorial/sound/SPI-intro.html), but Octave does not seem to load the implementations. This may be a problem with Octave's custom ClassLoader implementation.

Sample code that produces the problem:

octaveProblem.LoadResources.java:

public class LoadResource {
        public LoadResource() {
                System.out.println("Getters say:");
                Iterator<Getter> iterator = ServiceRegistry.lookupProviders(Getter.class);
                while (iterator.hasNext()) {
                        System.out.println("  Getter says: " + iterator.next().get());
                }
                System.out.println("Done!");
        }
        public static void main( String[] args ) {
                new LoadResource();
        }
}

octaveProblem.Getter.java:

public interface Getter {
        public String get();
}

octaveProblem.DefaultGetter.java:

public class DefaultGetter implements Getter {
        public String get() {
                return "GOT IT!";
        }
}

META-INF/services/octaveProblem.Getter:

octaveProblem.DefaultGetter

After creating a jar from these files, the expected result is shown when the jar is run outside of Octave:

Getters say:
  Getter says: GOT IT!
Done!

In Octave, the result is:

>> javaaddpath('octaveProblem-0.0.1-SNAPSHOT.jar')
>> javaObject('octaveProblem.LoadResource');
Getters say:
Done!
>>