So I was trying to create a custom furnace in 1.12.2, but whenever I tried to open the furnace, the game would crash. And then I tried to find out why, and apparently the code is outdated, and instead of using IInventory, I should use capabilities but I don't really know what it is and how to use it.

Capabilities are easy.

There's only three or four things you need to do.

 

The first is to remove any existing IInventory code.

Then add (in place of ItemStack[]) an ItemStackHandler. You can use one or multiple, depending on how you want to expose these as slots, or collection of slots, in the places that they're used.

Next, override getCapability. if (capability == CapabilityItemHandler.ITEM_HANDLER_CAPABILITY), you return one of your the ItemStackHandler fields. If you want more than one to be exposed, you can merge them with CombinedInvWrapper. Return super for any case you don't handle.

Third, override hasCapability and make it return true for any case where you return an ItemStackHandler (and call super for other cases). A lot of modders override this to return this.getCapability(capability, facing) != null;

 

The only "tricky" part is that if you want to expose different slots for different sides or do things like having output-only slots, but that's largely logic.

 

Fourth, you need to update your Gui/Container to use SlotItemHandler (or a subclass thereof) instead of Slot.

 

And a couple of examples:

https://github.com/Draco18s/ReasonableRealism/blob/1.12.1/src/main/java/com/draco18s/ores/entities/TileEntitySifter.java#L141

https://github.com/Draco18s/ReasonableRealism/blob/1.12.1/src/main/java/com/draco18s/ores/inventory/ContainerSifter.java#L27

https://github.com/Draco18s/ReasonableRealism/tree/1.12.1/src/main/java/com/draco18s/hardlib/api/internal/inventory

 

1 hour ago, Draco18s said:

Capabilities are easy.

There's only three or four things you need to do.

 

The first is to remove any existing IInventory code.

Then add (in place of ItemStack[]) an ItemStackHandler. You can use one or multiple, depending on how you want to expose these as slots, or collection of slots, in the places that they're used.

Next, override getCapability. if (capability == CapabilityItemHandler.ITEM_HANDLER_CAPABILITY), you return one of your the ItemStackHandler fields. If you want more than one to be exposed, you can merge them with CombinedInvWrapper. Return super for any case you don't handle.

Third, override hasCapability and make it return true for any case where you return an ItemStackHandler (and call super for other cases). A lot of modders override this to return this.getCapability(capability, facing) != null;

 

The only "tricky" part is that if you want to expose different slots for different sides or do things like having output-only slots, but that's largely logic.

 

Fourth, you need to update your Gui/Container to use SlotItemHandler (or a subclass thereof) instead of Slot.

 

And a couple of examples:

https://github.com/Draco18s/ReasonableRealism/blob/1.12.1/src/main/java/com/draco18s/ores/entities/TileEntitySifter.java#L141

https://github.com/Draco18s/ReasonableRealism/blob/1.12.1/src/main/java/com/draco18s/ores/inventory/ContainerSifter.java#L27

https://github.com/Draco18s/ReasonableRealism/tree/1.12.1/src/main/java/com/draco18s/hardlib/api/internal/inventory

 

I'll try to implement this into my code, and thanks for the response. This really helped me understand what they are.