When I attempt to use getAttributeModifiers to change the attributes of an item type defined as a Scala trait, the game crashes with an IllegalAccessError as such:

 

net.minecraft.util.ReportedException: Ticking player
at net.minecraft.network.NetworkSystem.networkTick(NetworkSystem.java:210) ~[NetworkSystem.class:?]
at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:806) ~[MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:687) ~[MinecraftServer.class:?]
at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:156) ~[integratedServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:536) [MinecraftServer.class:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_74]
Caused by: java.lang.IllegalAccessError: tried to access field net.minecraft.item.Item.ATTACK_DAMAGE_MODIFIER from class chuunimod.item.ItemManaWeapon$class
at chuunimod.item.ItemManaWeapon$class.getAttributeModifiers(ItemManaWeapon.scala:90) ~[itemManaWeapon$class.class:?]
at chuunimod.item.ItemArmorPairingManaWeapon.getAttributeModifiers(ItemArmorPairingManaWeapon.scala:20) ~[itemArmorPairingManaWeapon.class:?]
at net.minecraft.item.ItemStack.getAttributeModifiers(ItemStack.java:1043) ~[itemStack.class:?]
at net.minecraft.entity.EntityLivingBase.onUpdate(EntityLivingBase.java:2187) ~[EntityLivingBase.class:?]
at net.minecraft.entity.player.EntityPlayer.onUpdate(EntityPlayer.java:259) ~[EntityPlayer.class:?]
at net.minecraft.entity.player.EntityPlayerMP.onUpdateEntity(EntityPlayerMP.java:341) ~[EntityPlayerMP.class:?]
at net.minecraft.network.NetHandlerPlayServer.update(NetHandlerPlayServer.java:174) ~[NetHandlerPlayServer.class:?]
at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher$1.update(NetworkDispatcher.java:216) ~[NetworkDispatcher$1.class:?]
at net.minecraft.network.NetworkManager.processReceivedPackets(NetworkManager.java:308) ~[NetworkManager.class:?]
at net.minecraft.network.NetworkSystem.networkTick(NetworkSystem.java:195) ~[NetworkSystem.class:?]
... 5 more

 

The relevant trait:

trait ItemManaWeapon extends ItemChuuniItem { //ItemChuuniItem directly extends net.minecraft.item.Item
//omitted

override def getAttributeModifiers(slot:EntityEquipmentSlot, stack:ItemStack) = FMLCommonHandler.instance.getEffectiveSide match {
	case Side.CLIENT => super.getAttributeModifiers(slot, stack)
	case Side.SERVER => {
		val map = super.getAttributeModifiers(slot, stack)

		if(slot == EntityEquipmentSlot.MAINHAND && stack.hasTagCompound && stack.getTagCompound.getBoolean("active")) {
			map.put(SharedMonsterAttributes.ATTACK_DAMAGE.getAttributeUnlocalizedName, 
				new AttributeModifier(Item.ATTACK_DAMAGE_MODIFIER, "Weapon modifier", getAttackDmg(stack)-2, 0))
			map.put(SharedMonsterAttributes.ATTACK_SPEED.getAttributeUnlocalizedName, 
				new AttributeModifier(Item.ATTACK_SPEED_MODIFIER, "Weapon modifier", -(4-getAttackSpd(stack)), 0))
		}

		map
	}
}

//omitted
}

 

The code is throwing an IllegalAccessError at "Item.ATTACK_DAMAGE_MODIFIER", and I have no idea why outside of some Java/Scala interop bull****. Please help!

That's about what I figured. Do you know any way around it? I'd prefer not to make this an implementation detail of whatever mixes in the trait.

*sigh* thought so. Won't be pretty, but then neither is this whole process. Thanks!

That would be nice... Java/Scala interop always gets me down. "Seamless" my eye...