写了一个我的世界java版抓钩插件

import org.bukkit.entity.Player; import org.bukkit.event.EventHandler; import org.bukkit.event.Listener; import org.bukkit.event.inventory.InventoryCloseEvent; import org.bukkit.inventory.ItemStack; public class FlyingOnRetractFishingRodPlugin extends JavaPlugin implements Listener {   @Override   public void onEnable() {     getServer().getPluginManager().registerEvents(this, this);   }   @EventHandler   public void onInventoryClose(InventoryCloseEvent event) {     Player player = (Player) event.getPlayer();     ItemStack fishingRod = player.getInventory().getItemInMainHand();     if (fishingRod != null && fishingRod.hasItemMeta() && fishingRod.getItemMeta().hasDisplayName() && fishingRod.getItemMeta().getDisplayName().equals("钓鱼竿")) {       player.setVelocity(player.getLocation().getDirection().multiply(2));     }   } }