I created a capability which is supposed to store ItemStacks the player has dropped. I do this by having an ArrayList in my capability class. I can add and get the items correctly via the getLostItems getter, but whenever I rejoin the list is empty, indicating that the list isn't saved. I tried to match the saveAllItems and loadAllItems in the ItemStackHelper class, but I am not sure where I went wrong.

 

Storage class:

        @Nullable
        @Override
        public NBTBase writeNBT(Capability<ILostItemsCapability> capability, ILostItemsCapability instance, EnumFacing side)
        {
            return ItemNBTHelper.saveItemList(new NBTTagCompound(), instance.getLostItems());
        }

        @Override
        public void readNBT(Capability<ILostItemsCapability> capability, ILostItemsCapability instance, EnumFacing side, NBTBase nbt)
        {
            ItemNBTHelper.loadItemList((NBTTagCompound) nbt, instance.getLostItems());
        }

ItemNBTHelper:

    public static NBTTagCompound saveItemList(NBTTagCompound tag, List<ItemStack> itemStacks)
    {
        NBTTagList tagList = new NBTTagList();

        for(int i = 0; i < itemStacks.size(); ++i)
        {
            ItemStack itemStack = itemStacks.get(i);

            if(!itemStack.isEmpty())
            {
                NBTTagCompound compound = new NBTTagCompound();
                compound.setByte("Slot", (byte)i);
                itemStack.writeToNBT(compound);
                tagList.appendTag(compound);
            }
        }

        if(!tagList.hasNoTags())
        {
            tag.setTag("Items", tagList);
        }

        return tag;
    }

    public static void loadItemList(NBTTagCompound tag, List<ItemStack> itemStacks)
    {
        NBTTagList tagList = tag.getTagList("Items", 10);

        for(int i = 0; i < tagList.tagCount(); ++i)
        {
            NBTTagCompound compound = tagList.getCompoundTagAt(i);
            int slot = compound.getByte("Slot") & 255;

            if(slot >= 0 && slot < itemStacks.size())
            {
                itemStacks.set(slot, new ItemStack(compound));
            }
        }
    }

 

Edited March 1, 20187 yr by That_Martin_Guy

ItemStackHandler uses a NonNullList. I do not want there to be a limit on how many items there are in the list, and any of the other features that class provides is useless for me.

I was following the original code too closely, apparently. Doing what you said seems to have fixed it!

 

New saving and loading code:

    public static NBTTagCompound saveItemList(NBTTagCompound tag, List<ItemStack> itemStacks)
    {
        NBTTagList tagList = new NBTTagList();

        for(int i = 0; i < itemStacks.size(); ++i)
        {
            ItemStack itemStack = itemStacks.get(i);

            if(!itemStack.isEmpty())
            {
                NBTTagCompound compound = itemStack.writeToNBT(new NBTTagCompound());
                tagList.appendTag(compound);
            }
        }

        if(!tagList.hasNoTags())
        {
            tag.setTag("Items", tagList);
        }

        return tag;
    }

    public static void loadItemList(NBTTagCompound tag, List<ItemStack> itemStacks)
    {
        NBTTagList tagList = tag.getTagList("Items", 10);

        for(int i = 0; i < tagList.tagCount(); ++i)
        {
            NBTTagCompound compound = tagList.getCompoundTagAt(i);
            itemStacks.add(new ItemStack(compound));
        }
    }