Saving Inventories to files

Hello!

I'm working on a minigame plugin for a friend of mine however I got a little stuck on one of its features.
He asked me to save a players inventory before he enters a game and then he gets his inventory back after its finished.
I looked around on these forums and found some threads with a LOT of codes but some are outdated and gives errors. Also I don't fully understand what they do and I want to learn how to save them.

Regards,
Deamon

 

You can make a hashmap with the key UUID and value ItemStack[] and put the player.getInventory().getContents(); erin.

Code:java

Map<UUID, ItemStack[]> inventory = new HashMap<UUID, ItemStackp[>();
inventory.put(player.getUniqueId(), player.getInventory().getContents());

 

I've made this as a little test for when a player returns to gamemode 0 (Survival) he would get his armor back and his items.
However it doesn't work. I also tried it with a command /inv save and /inv load and that did work however this doesn't.
Any idea why not?

Code:java

@EventHandler
    public void onGamemodeChange(PlayerGameModeChangeEvent e) {
        Map<UUID, ItemStack[]> inv = new HashMap<UUID, ItemStack[]>();
        Map<UUID, ItemStack[]> armour = new HashMap<UUID, ItemStack[]>();
 
        Player p = (Player) e.getPlayer();
        GameMode nieuw = e.getNewGameMode();
 
        if(nieuw == GameMode.SURVIVAL) {
            if(inv.containsKey(p.getUniqueId()) && armour.containsKey(p.getUniqueId())) {
                p.getInventory().setContents(inv.get(p.getUniqueId()));
                p.getInventory().setArmorContents(armour.get(p.getUniqueId()));
            }
        } else if(nieuw == GameMode.CREATIVE) {
            if(inv.containsKey(p.getUniqueId()) && armour.containsKey(p.getUniqueId())) {
                armour.replace(p.getUniqueId(), p.getInventory().getArmorContents());
                inv.replace(p.getUniqueId(), p.getInventory().getContents());
            } else if(!inv.containsKey(p.getUniqueId()) && !armour.containsKey(p.getUniqueId())) {
                armour.put(p.getUniqueId(), p.getInventory().getArmorContents());
                inv.put(p.getUniqueId(), p.getInventory().getContents());
            }
        }
    }

 

Please help!