Solved Storing ItemStack not working

I am trying to save the BackPack when a player closes it. Whenever I try to open it everything is null. Is this because of the HashMap type for the entry not allowing any items in the array?

Code:

package com.trueboxguy.backpack;

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.entity.Player;
import org.bukkit.inventory.Inventory;
import org.bukkit.inventory.ItemStack;


import java.util.HashMap;
import java.util.UUID;

public class InventoryHandler {
    HashMap<UUID,ItemStack[]> inventories = new HashMap<>();
    Player player;

    /**
     * Constructor.
     *
     * @param player - The player you want to create a BackPack for.
     */
    public InventoryHandler(Player player) {
        UUID playersUUID = player.getUniqueId();
        this.player = player;
        if (!inventories.containsKey(playersUUID)) {
            inventories.put(playersUUID, new ItemStack[]{});
        }
    }

    /**
     * Opens the players backpack
     *
     * @return boolean - If the player has a BackPack (it should as the constructor creates a BackPack for the player)
     */
    public boolean open() {
        UUID playersUUID = player.getUniqueId();
        if (inventories.containsKey(playersUUID)) {
            Inventory inventory = Bukkit.createInventory(null, 5*9, ChatColor.GOLD + "BackPack");
            inventory.setContents(inventories.get(playersUUID));
            player.openInventory(inventory);
            return true;
        }
        return false;
    }

    /**
     * Updates a players BackPack
     *
     * @param player - The player who's backpack you want to update.
     * @param newInventory -  The inventory that you want to replace the player's old backpack.
     *
     * @return boolean - If the player has an inventory
     */
    public boolean set(Player player, Inventory newInventory) {
        UUID playersUUID = player.getUniqueId();
        if (inventories.containsKey(playersUUID)) {
            inventories.put(playersUUID,newInventory.getContents()); //it overwrites. See javadoc
            return true;

        }
        return false;
    }
}

 

I don't know if it will fix your problem, but use the UUID string instead of the UUID object.

Code:

Map<String, ItemStack[]> backpacks = new HashMap<>();

String UUID = player.getUniqueId().toString();

I'm not in my environment right now, yet, it should be something very similar to the code above.

 

I need to make it static. It was so obvious that I thought I already did it

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

@timtower What I meant was that I need to make the
HashMap inventories static. Because whenever I made a new instance there would be a new instance of the HashMap. This mean't that it wouldn't be stored.

 

@timtower many people have had that idea. The bad thing about it is that when I will make my backpack have more features and maybe run more methods. It will be harder. You're right that it would be better right now.