Hello, I'm trying to store data in the block's nbt data, but i have no idea how to do this, apparently im supposed to use capabilities but there's so little documentation, and I have no idea how to do this, can someone please provide me some example code?

You only need a capability if it is not your BlockEntity.

https://forge.gemwire.uk/wiki/Capabilities (includes a simple example at the bottom but for a serializable Entity capability rather than a BlockEntity - same principle applies).

 

If it is your BlockEntity

https://forge.gemwire.uk/wiki/Block_Entities#Storing_Data_within_your_BlockEntity

Hey I did all that, tbh i've been struggling the last hour trying to make the thing, I did everything but now I'm trying to add the capability to the block and then set it when it is placed down, this is the code:

	@NotNull
	@Override
	public <T> LazyOptional<T> getCapability(@NotNull Capability<T> cap, @Nullable Direction side) {
		return LazyOptional.of(ATMCapability::new).cast();
	}

	@Override
	public void onPlace(BlockState state, Level world, BlockPos pos, BlockState blockState, boolean p_60570_) {
	    world.getCapability(ATMCapability.INSTANCE).ifPresent((cap) -> {
	        cap.setPrivateKey("test");
			cap.setAtmId("test");
		});

		System.out.println("ATM created!");
		System.out.println("Private key: " + world.getCapability(ATMCapability.INSTANCE).orElseThrow(NullPointerException::new).getPrivateKey());
		System.out.println("ATM ID: " + world.getCapability(ATMCapability.INSTANCE).orElseThrow(NullPointerException::new).getAtmId());
	}

I have no idea if this is even correct, but i dont know what else to do, it keeps giving me the nullpointerexception which means that its not being saved

Read the part about attaching capabilities on the wiki.

Yes, but I don't understand the AttachCapabilitiesEvent<Entity>, how does that attach it to the atm block, I tried subscribing and all of that, changing code i dont know what to do, can you please explain it?

Replace Entity with BlockEntity then check if you want to attach to that BlockEntity using instanceof

 

e.g. https://github.com/MehVahdJukaar/WIPsuppMULTI/blob/cff33b050cf564d4fffb2ecfff8cd888528fe82d/forge/src/main/java/net/mehvahdjukaar/supplementaries/common/capabilities/forge/CapabilityHandler.java

or one of the other examples from this search:

https://github.com/search?l=&p=3&q=AttachCapabilitiesEvent+BlockEntity&ref=advsearch&type=Code

Hey, yeah i did that and made a blockentity and now im getting this error 

class ...atm.capability.ATMCapability cannot be cast to class ...atm.capability.ATMCapabilityInterface

 

Edited January 21, 20232 yr by Anonomys

If you don't know what that error means you are in the wrong forum.

You want a "learning java" forum.

Yes but its not being cast to that anywhere, ive looked through everything

Huh?

A capability implementation must implement its own interface.

You don't even show the full stacktrace of the error which will tell you where the cast occurs (maybe implicitly inserted by the compiler because of generics?).

 

If you want further help, you need to show everything you are doing.

Posting snippets of code out of context and truncated error messages just means your question unanswerable and will probably just mean your question gets ignored.

We are not going to waste our time chasing you for relevant information. It is you that wants help.

Edited January 21, 20232 yr by warjort

I found where the error was, in the blockentity class the getCapability was returning the ATMCapability.INSTANCE instead of the ATMCapabilityImplementation. Sorry for taking your time