Help on ListNBT of items

public void setMagic(ItemStack itemstack, Magic magic, int slotNumber) {
		CompoundNBT compoundnbt = itemstack.getOrCreateChildTag("Spell_book");
		if (!compoundnbt.contains("Magics", 0)) {
			compoundnbt.putIntArray("Magics", new ArrayList<>());
			itemstack.write(compoundnbt);
		}
		ListNBT listnbt = compoundnbt.getList("Magics", Constants.NBT.TAG_COMPOUND);
		List<Integer> list = Lists.newArrayList();
		if (!listnbt.isEmpty()) {
			CompoundNBT slot = new CompoundNBT();
			slot.putInt("Magic", magic.id);
			itemstack.write(slot);
			listnbt.set(slotNumber, slot);
			compoundnbt.put("Magics", listnbt);
		}
		itemstack.write(compoundnbt);
		Minecraft.getInstance().player.sendMessage(new StringTextComponent(Integer.toString(compoundnbt.getList("Magics", 10).getInt(0))), null);
	}

When I call the above method, I think that the value of magic id is displayed in the chat column, but no matter what I put in magic id, 0 is displayed in chat. What's wrong?