Java and Scala not playing well together

[gcewing]

I'm developing an add-on for Project Red, and weird things are happening with the way Java and Scala interact. Everything compiles fine, but some things misbehave at run time.

 

1) I have a subclass of JItemMultiPart written in Java that overrides some Item methods, such as registerIcons. But my overrides are never called -- it calls the base methods defined in class Item instead. If I replace JItemMultiPart with a re-implementation of it in pure Java, my overrides are called as expected.

 

2) Calling methods of a TileMultipart that are defined in TileEntity, e.g. getBlockType and markDirty, causes a Method Not Found exception at run time. These calls work if I explicitly cast the TileMultipart to TileEntity, however.

 

It seems like the runtime is not recognising that these Scala-implemented classes inherit from java base classes.

 

There is no Scala in my own code, only Java.

 

I've tried compiling with two different versions of javac, javac 1.6.0_51 and javac 1.7.0-b222, with the same result. I'm on MacOSX 10.6.8.

 

None of this was happening when I first started working on the mod a few months ago, but back then I was using my own custom builds of ForgeMultipart and Project Red for 1.7. The only thing I can think of that's changed is that I'm now compiling against the official 1.7.10 releases.

 

Anyone have any idea what might be happening? I can work around these problems for now, but they're disconcerting and I'd like to get to the bottom of them.