[SOLVED] [1.8] Strange AbstractMethodError Crash With Lambda

[Choonster]

I've run into a strange issue where using a lambda to implement

ItemMeshDefinition

crashes the game with an

AbstractMethodError

any time the item is rendered in a GUI. This only happens in the obfuscated client, not in the development environment.

 

I've set up a small test case here. The lambda is used here.

 

To reproduce, simply open the mod's creative tab or spawn in its block. The block will render without issue in the world, but as soon as it's rendered in a GUI or a player's hand the game crashes.

 

You can see the crash report here.

 

Does anyone know why this happens or how to fix it? It seems like it may be some weird interaction between lambdas and the reobfuscation process.

[kauan99]

I don't know much about 1.8 or models, but that lambda seems weird... Are you sure that's what you meant to write?

[Choonster]

  On 9/23/2015 at 10:15 AM, kauan99 said:

I don't know much about 1.8 or models, but that lambda seems weird... Are you sure that's what you meant to write?

 

Yes, it's just mapping to a constant model location regardless of the

ItemStack

's metadata/NBT.

[kauan99]

java thinks you're invoking an interface method without implementation though. well if only I knew more about that model stuff...

[Choonster]

  On 9/23/2015 at 10:25 AM, kauan99 said:

java thinks you're invoking an interface method without implementation though. well if only I knew more about that model stuff...

 

Lambdas can be used in place of any interface with a single method (like

ItemMeshDefinition

), they act like an implementation of the interface with the lambda's body as the method body.

 

This works in the development environment, just not in the obfuscated client.

[kauan99]

I didn't know there was such interface. then your lambda seems fine. maybe it's the java version you're targeting?

 

I don't know the language used in build.gradle, but maybe there's something wrong there? for instance, I was told I should choose java version for building using these lines:

 

sourceCompatibility = 1.8
targetCompatibility = 1.8

 

but you do something different.

[Choonster]

Thanks diesieben07, that works perfectly.

 

I looked at the bytecode earlier using Bytecode Viewer and noticed the INVOKEDYNAMIC instruction (though I wasn't fully aware of what it did), but it seems that the program doesn't know how to display it properly.