[Solved] 1.16 Storing ArrayList<BlockPos> to NBT

[Titmar]

I am currently stuck at storing (and reading) an ArrayList of BlockPos to NBT. I found a thread where they tell you to use a NBTTagList. This does not seem to exist in 1.16 anymore. I know there is the NBTUtil methods for BlockPos which is returning me a new CompoundNBT. The idea I have is to use the NBTCompound#put(String key, INBT value) method and just add a incremental number to my key for every object in my ArrayList. But that sounds dirty to me. Is there a better way?

Edited April 1, 2021 by Titmar
Problem solved

[Draco18s]

To serialize:

Store the length of the array.

Push all serialized BlockPos values.

To deserialize:

Read the length of the array.

Deserialize that many BlockPos values.

[Titmar]

So basically the idea i had. I just tested it and I have no idea why it wont work.

 

	@Override
	public CompoundNBT write(CompoundNBT compound) {
		super.write(compound);
		compound.putInt("containerArray", containers.size());
		int i = 0;
		for (BlockPos bp : containers) {
			compound.put("pos" + i, NBTUtil.writeBlockPos(bp));
			i++;
		}
		return compound;
	}

	@Override
	public void read(BlockState state, CompoundNBT nbt) {
		super.read(state, nbt);
		int size = nbt.getInt("containerArray");
		for (int i = 0; i <= size; i++) {
			BlockPos bp = NBTUtil.readBlockPos((CompoundNBT) nbt.get("pos" + i));
			containers.add(bp);
		}
	}

 

[kiou.23]

for (int i = 0; i <= size; i++)

size is the amount of items in the list. but the list is 0-indexed, meaning the items indexes goes from 0 to size - 1

you're trying to get an element at an index which doesn't exist

[Titmar]

This is actually what i was looking for - a sucessor of the NBTTagList. Thank you sieben. Makes it look way cleaner.

It still does not work though.

 

	@Override
	public CompoundNBT write(CompoundNBT compound) {
		super.write(compound);
		ListNBT nbt = new ListNBT();
		for(BlockPos pos : containers) {
			nbt.add(NBTUtil.writeBlockPos(pos));
		}
		compound.put("containerArray", nbt);
		return compound;
	}

	@Override
	public void read(BlockState state, CompoundNBT compound) {
		super.read(state, compound);
		ArrayList<BlockPos> list = new ArrayList<BlockPos>();
		ListNBT nbt = (ListNBT) compound.get("containerArray");
		for(int i = 0; i < nbt.size(); i++) {
			list.add(NBTUtil.readBlockPos(nbt.getCompound(i)));
		}
		this.containers = list;
	}

Or would i use the compound#getList(name, type) method instead? And if so, what do i put as type?

[Titmar]

11 minutes ago, diesieben07 said:

Elaborate.

When im accessing the NBT data from a different point (right clicking  the block and outputting into the logger) it shows me an empty NBTList while the private list of the TE has content. After reloading the world all data is lost. Since i dont know how to trigger a read/write i cant tell where the mistake is. Adding a debug message right into the read/write methods does not work either. I dont get any Logger output at all. Seems weird that both functions arent triggered at all...  Will upload to git so you have a full overview.

 

https://github.com/titmar/Caravans/blob/main/src/main/java/io/github/titmar/caravans/common/tile/MarketTileEntity.java

[Titmar]

• Ahh, it has been the markDirty part. I knew i missed some crucial part that calls the read/write.
• As for the HashSet, this is subject to change anyway. In the future i will need to store way more data alongside the position. For now I just wanted to get a proof of concept which I can expand on.
• I guess I was using the wrong nethod there, it should be getTileData(). The idea was to check if anything has been writen onto the NBTTag. Because if anything has been writen in there and it still didnt work the problem would have been in the read method. As we know now neither was the case.

Thank you for your help!