DrinksGUI

public class DrinksGUI extends JavaPlugin implements Listener {

    public static Inventory GUI = Bukkit.createInventory(null, 9, "§4§nDrinks");
    @SuppressWarnings({"unchecked", "rawtypes"})
    public HashMap<Player, Entity> Menu = new HashMap<Player, Entity>();

    public static void setItems() {
        ItemStack Coke = new ItemStack(Material.POTION, 1, (byte) 2);
        ItemMeta Cokemeta = Coke.getItemMeta();
        Cokemeta.setDisplayName(ChatColor.RED + "Cola");
        Coke.setItemMeta(Cokemeta);
        GUI.setItem(3, Coke);

        ItemStack Lemonade = new ItemStack(Material.POTION, 1, (byte) 5);
        ItemMeta Lemonademeta = Lemonade.getItemMeta();
        Lemonademeta.setDisplayName(ChatColor.YELLOW + "Lemonade");
        Lemonade.setItemMeta(Lemonademeta);
        GUI.setItem(4, Lemonade);

        ItemStack Vodka = new ItemStack(Material.POTION, 1, (byte) 9);
        ItemMeta Vodkameta = Vodka.getItemMeta();
        Vodkameta.setDisplayName(ChatColor.AQUA + "Vodka");
        Vodka.setItemMeta(Vodkameta);
        GUI.setItem(5, Vodka);
    }

    @SuppressWarnings("unused")
    private static void setItem(int i, ItemStack lemonade) {
        // TODO Auto-generated method stub

    }

    public void onEnable() {
        Bukkit.getServer().getLogger().info("Drinks Enabled!");
        Bukkit.getServer().getPluginManager().registerEvents(this, this);
        setItems();
    }

    public void onDisable() {
        Bukkit.getServer().getLogger().info("Drinks Disabled!");
    }

    @EventHandler
    public void onPlayerJoin(PlayerJoinEvent event) {
        event.getPlayer().getInventory().addItem(new ItemStack(Material.CHEST, 1));
        ItemStack Chest = new ItemStack(Material.CHEST, 1);
        ItemMeta Chestmeta = Chest.getItemMeta();
        Chestmeta.setDisplayName(ChatColor.BLUE + "Drink Selector");
        Chest.setItemMeta(Chestmeta);

    }

    @EventHandler
    public void OnInventoryClick(InventoryClickEvent event) {
        if (!ChatColor.stripColor(event.getInventory().getName()).equalsIgnoreCase("Drinks"))
            return;
        Player player = (Player) event.getWhoClicked();
        event.setCancelled(true);

        if (event.getCurrentItem() == null || event.getCurrentItem().getType() == Material.AIR || event.getCurrentItem().hasItemMeta()) {
            player.closeInventory();
            return;
        }
        switch (event.getCurrentItem().getType()) {
            case POTION:
                player.getInventory().addItem(new ItemStack(Material.POTION, 1, (byte) 3));
                player.getInventory().addItem(new ItemStack(Material.POTION, 1, (byte) 9));
                player.getInventory().addItem(new ItemStack(Material.POTION, 1, (byte) 5));
                player.closeInventory();
                break;

            default:
                player.closeInventory();
                break;
        }
    }

    @EventHandler
    public void onPlayerRespawn(PlayerRespawnEvent event) {
        Player player = event.getPlayer();
        player.getInventory();
        ItemStack item = new ItemStack(Material.CHEST);
        item.setAmount(1);
        ItemMeta meta = item.getItemMeta();
        meta.setDisplayName(ChatColor.AQUA + "Drinks");
        item.setItemMeta(meta);
    }

    @EventHandler
    public void onPlayerInteract(PlayerInteractEvent e) {
        Action a = e.getAction();
        ItemStack is = e.getItem();

        if (a == Action.PHYSICAL || is == null || is.getType() == Material.AIR)
            return;

        if (is.getType() == Material.CHEST)
            e.getPlayer().openInventory(GUI);
    }
}