I'm trying to register a GUI handler for my mod, and it gives me this error:

net.minecraftforge.fml.common.LoaderExceptionModCrash: Caught exception from The Minecraft RWBY Mod (rwbymod)
Caused by: java.lang.NullPointerException
	at net.minecraftforge.fml.common.network.NetworkRegistry.registerGuiHandler(NetworkRegistry.java:229)
	at com.rwbymod.z_proxy.CommonProxy.init(CommonProxy.scala:21)
	at com.rwbymod.z_proxy.ClientProxy.init(ClientProxy.scala:10)

 

If I go to NetworkRegistry, the offending line shows this:

FMLLog.log(Level.ERROR, "Mod of type %s attempted to register a gui network handler during a construction phase", mod.getClass().getName());

 

What's odd is that I'm registering the GUI handler in the Init phase, while in a Java version of the same mod I register it in PreInit... and it works. I switch over to Scala, and suddenly it stops working.

 

Here's my code:

 

CommonProxy.scala (ClientProxy just calls the methods here, plus irrelevant rendering stuffs):

class CommonProxy {

  def preInit {
    // irrelevant
  }

  def init {
    NetworkRegistry.INSTANCE.registerGuiHandler(RWBYMod.instance, new GuiHandler())
  }

  def postInit {}

}

 

GuiHandler.scala:

object GuiHandler {
  val guiScroll = 0
}

class GuiHandler extends IGuiHandler {
  import GuiHandler._

  def getServerGuiElement(id:Int, player:EntityPlayer, world:World, x:Int, y:Int, z:Int) = id match {
    case _ => null
  }

  def getClientGuiElement(id:Int, player:EntityPlayer, world:World, x:Int, y:Int, z:Int) = id match {
    case i if i == guiScroll => new GuiScroll()
    case _ => null
  }

}

 

Edited April 12, 20178 yr by tripl3dogdare

Your RWBYMod.instance is null at the point you call NetworkRegistry#registerGuiHandler. Do you have the variable annotated with @Instance?

Yes, in my main mod file I have this:

@Instance(MODID) var instance = null

 

That's how I've done it in a couple other Scala mods - however, none of them had GUIs, which may be why I'm only running into this issue now.

Do you by any chance have a Git repository with your Scala code? Or a branch on your Java-version repository? It would make debugging a lot easier.

Edited April 12, 20178 yr by larsgerrits

Here is the main repo: https://github.com/tripl3dogdare/rwbymod

And the scala branch: https://github.com/tripl3dogdare/rwbymod/tree/scala

Thank you, that seems to have fixed it ^-^ I guess I haven't broken out of my Java habits as nicely as I'd have hoped.