我正在尝试制作一个minecraft插件，它是一个游戏模式改变器GUI当我单击一个块时，它会改变我的游戏模式。我的插件成功地显示在控制台中，让我查看游戏中的GUI，但不做任何我编码它要做的事情：

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.GameMode;
import org.bukkit.Material;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.inventory.InventoryClickEvent;
import org.bukkit.inventory.Inventory;
import org.bukkit.inventory.ItemStack;
import org.bukkit.plugin.java.JavaPlugin;

public class Main extends JavaPlugin {

    @Override
    public void onEnable() {
        getLogger().info("[GamemodeGUI] Plugin has been enabled!");
    }

    @Override
    public void onDisable() {
        getLogger().info("[GamemodeGUI] Plugin has been disabled!");
    }

    public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) {
        Player player = (Player) sender;
        if (cmd.getName().equalsIgnoreCase("gmgui")) {
            player.openInventory(myInventory);
        }
        return true;
    }

    public static Inventory myInventory = Bukkit.createInventory(null, 9, "GamemodeGUI");

    static {
        myInventory.setItem(0, new ItemStack(Material.IRON_BLOCK, 1)); // Survival
        myInventory.setItem(1, new ItemStack(Material.DIAMOND_BLOCK, 1)); // Creative
        myInventory.setItem(2, new ItemStack(Material.GOLD_BLOCK, 1)); // Adventure
        myInventory.setItem(3, new ItemStack(Material.LAPIS_BLOCK, 1)); // Spectator

        myInventory.setItem(8, new ItemStack(Material.STAINED_GLASS, 1)); // Cancel
    }

    @EventHandler
    public void onInventoryClick(InventoryClickEvent event) {

        Player player = (Player) event.getWhoClicked();
        ItemStack clicked = event.getCurrentItem();
        Inventory inventory = event.getInventory();
        if (inventory.getName().equals(myInventory.getName())) {

            if (clicked.getType() == Material.IRON_BLOCK) {
                event.setCancelled(true);
                player.closeInventory();

                if (player.hasPermission("gamemodegui.survival")) {
                    player.setGameMode(GameMode.SURVIVAL);
                    player.sendMessage(ChatColor.RED + "Gamemode set to survival");
                } else {
                    player.sendMessage(ChatColor.RED + "Error: You do not have the permission to use that command ");
                }

            }

            else if (clicked.getType() == Material.DIAMOND_BLOCK) {
                event.setCancelled(true);
                player.closeInventory();

                if (player.hasPermission("gamemodegui.creative")) {
                    player.setGameMode(GameMode.CREATIVE);
                    player.sendMessage(ChatColor.RED + "Gamemode set to creative");
                } else {
                    player.sendMessage(ChatColor.RED + "Error: You do not have the permission to use that command ");
                }

            }

            if (clicked.getType() == Material.LAPIS_BLOCK) {
                event.setCancelled(true);
                player.closeInventory();

                if (player.hasPermission("gamemodegui.adventure")) {
                    player.setGameMode(GameMode.ADVENTURE);
                    player.sendMessage(ChatColor.RED + "Gamemode set to adventure");
                } else {
                    player.sendMessage(ChatColor.RED + "Error: You do not have the permission to use that command ");
                }

            }

            if (clicked.getType() == Material.IRON_BLOCK) {
                event.setCancelled(true);
                player.closeInventory();

                if (player.hasPermission("gamemodegui.spectator")) {
                    player.setGameMode(GameMode.SPECTATOR);
                    player.sendMessage(ChatColor.RED + "Gamemode set to spectator");
                } else {
                    player.sendMessage(ChatColor.RED + "Error: You do not have the permission to use that command ");
                }
            } else {
                event.setCancelled(true);
                player.closeInventory();
            }
        }
    }
}

在游戏中，我点击其中一个方块，我可以拖动它，它什么也不做。它也不会把方块放回去，直到我重新启动服务器。

我是java和编码的新手。