I have an ItemStack with a single piece of e.g. coal; when I call itemStack.serializeNBT I get:

{id:"minecraft:coal",Count:1b,Damage:0s}

 

When I then try to deserialize the tag I get:

1xtile.air@0

 

I found that deserializeNBT calls new ItemStack(compound); it calls Item.getByNameOrId("minecraft:coal")  which returns 1xitem.coal@0. For some reason,  this fails and causes ItemStack to have 1xtile.air@0 :

this.item = Item.getByNameOrId("minecraft:coal");

This works, however:

itemStack = new ItemStack(Item.getByNameOrId("minecraft:coal"));

 

Am I doing something wrong calling

nbt.setTag("mystack", itemStack.serializeNBT());

and

itemStack.deserializeNBT(tag.getTag("mystack"));

?

 

ItemStack:

    public NBTTagCompound serializeNBT()
    {
        NBTTagCompound ret = new NBTTagCompound();
        this.writeToNBT(ret);
        return ret;
    }

    public void deserializeNBT(NBTTagCompound nbt)
    {
        // TODO do this better while respecting new rules
        final ItemStack itemStack = new ItemStack(nbt);
        this.stackTagCompound = itemStack.stackTagCompound;
        this.capNBT = itemStack.capNBT;
    }

 

So effectively, that's what those methods already do...

 

Wow I totally missed that it's parsing the NBT to a new local ItemStack and then ignores it... thanks.