Need help understanding this [1.15.1]

[Danieldrd]

@Override
    public void read(CompoundNBT tag) {
        CompoundNBT invTag = tag.getCompound("inv");
        getHandler().deserializeNBT(invTag);
        super.read(tag);
    }

    @Override
    public CompoundNBT write(CompoundNBT tag) {
        CompoundNBT compound = getHandler().serializeNBT();
        tag.put("inv", compound);
        return super.write(tag);
    }

    private ItemStackHandler getHandler() {
        if (handler == null) {
            handler = new ItemStackHandler(1);
        }
        return handler;
    }

    @Nonnull
    @Override
    public <T> LazyOptional<T> getCapability(@Nonnull Capability<T> cap) {
        if (cap == CapabilityItemHandler.ITEM_HANDLER_CAPABILITY) {
            return LazyOptional.of(() -> (T) getHandler());
        }
        return super.getCapability(cap);
    }

 

I've been watching YouTube tutorials and when trying to make a tile entity block which holds items, he wrote this. Could someone clarify what is going on in this section of code? Thanks.

[Danieldrd]

6 minutes ago, diesieben07 said:

• You can learn more about capabilities in the documentation.
• The lazy initialization in getHandler is pointless. LazyOptional is already lazy. Plus you are calling getHandler in readFromNbt, which is like, the first thing that happens in a tile entity. So there isn't even any point lazily initializing the handler. Just create it in the constructor and use a final field.

Thanks!