I need a .java code for an inventory command in a text-based adventure game where a player can type "inventory" and it will display their inventory. There needs to be an "equip" item and an "unequip" item command, as well as a "leave inventory" command. Please do not just send me an AI-generated code! The code should work, for example, "equip pickaxe", "unequip pickaxe", and it needs to show that it's in an inventory slot with 10 item slots.