Checking if player inventory is full

[Efrenit]

I'm trying to make a system that will go to the chest automatically and put all the items in the chest. However, I can't check if the inventory is full. I tried: 
!Arrays.asList(Minecraft.getMinecraft().player.inventoryContainer.getInventory()).contains(null)
Minecraft.getMinecraft().player.inventoryContainer.getSlot(i).getStack().getCount() (with for)
Minecraft.getMinecraft().player.inventoryContainer.getSlot(i).getStack().isEmpty() (with for)
It either just doesn't work, or doesn't work with a huge bunch of exceptions in the logs
I need to check if there are any items in the inventory slots, without slots for armor and left hand.
Doing all this on 1.12.2, 14.23.5.2860
Thanks for taking the time for a little dumb me

[ChampionAsh5357]

The version you are using is no longer supported on this forum.

Please update to a modern version of Minecraft to receive support.

Currently supported versions are 1.19.2 (Latest) and 1.18.2 (LTS).