Utility to rename custom Bukkit inventories without opening a new inventory (only works with Inventories created by Bukkit.createInventory!)

InventoryUtil.java

package net.darkseraphim.utils;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;

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

public class InventoryUtil
{
    
    private static String version;
    
    private static final Field iinvField;
    
    private static final Field titleField;
    
    private static final Field handleField;
    
    private static final Field containerCounterField;
    
    private static final Constructor openWindowPacketConstructor;
    
    private static final Field playerConnectionField;
    
    private static final Method sendPacket;

    static
    {
        String[] parts = Bukkit.class.getName().split(".");
        if(parts.length == 4)
            version = "";
        else
            version = "." + parts[4];
        Field tiinv = null;
        Field ttitle = null;
        Field thandle = null;
        Field tcontainerCounter = null;
        Constructor topenWindowPacket = null;
        Field tplayerConnection = null;
        Method tsendPacket;
        try
        {
            tiinv = getVersionedClass("org.bukkit.craftbukkit.inventory.CraftInventory").getDeclaredField("inventory");
            tiinv.setAccessible(true);
            ttitle = getVersionedClass("org.bukkit.craftbukkit.inventory.CraftInventoryCustom$MinecraftInventory").getDeclaredField("title");
            ttitle.setAccessible(true);
            thandle = getVersionedClass("org.bukkit.craftbukkit.entity.CraftEntity").getDeclaredField("handle");
            thandle.setAccessible(true);
            tcontainerCounter = getVersionedClass("net.minecraft.server.EntityPlayer").getDeclaredField("containerCounter");
            tcontainerCounter.setAccessible(true);
            thandle = getVersionedClass("org.bukkit.craftbukkit.entity.CraftEntity").getDeclaredField("handle");
            thandle.setAccessible(true);
            topenWindowPacket = getVersionedClass("net.minecraft.server.PacketPlayOutOpenWindow").getDeclaredConstructor(int.class, int.class, String.class, int.class, boolean.class);
            topenWindowPacket.setAccessible(true);
            tplayerConnection = getVersionedClass("net.minecraft.server.EntityPlayer").getDeclaredField("playerConnection");
            tplayerConnection.setAccessible(true);
            tsendPacket = getVersionedClass("net.minecraft.server.PlayerConnection").getDeclaredMethod("sendPacket", topenWindowPacket.getDeclaringClass().getSuperclass());
            tsendPacket.setAccessible(true);
        }
        catch(Exception ex) // Any would do, regardless
        {
            throw new ExceptionInInitializerError(ex);
        }
        iinvField = tiinv;
        titleField = ttitle;
        handleField = thandle;
        containerCounterField = tcontainerCounter;
        openWindowPacketConstructor = topenWindowPacket;
        playerConnectionField = tplayerConnection;
        sendPacket = tsendPacket;
    }
    
    private static Class getVersionedClass(String className) throws ClassNotFoundException
    {
        if(className.startsWith("net.minecraft.server"))
            if(version.isEmpty())
                return Class.forName(className);
            else
                return Class.forName(String.format("net.minecraft.server%s.%s", version, className.substring("net.minecraft.server.".length())));
        else if(className.startsWith("org.bukkit.craftbukkit"))
            if(version.isEmpty())
                return Class.forName(className);
            else
                return Class.forName(String.format("net.minecraft.server%s.%s", version, className.substring("org.bukkit.craftbukkit.".length())));
        throw new IllegalArgumentException("Not a versioned class!");
    }
    
    public static void renameInventory(Player player, Inventory inventory, String title)
    {
        try
        {
            Object iinv = iinvField.get(inventory);
            titleField.set(iinv, title);
            Object handle = handleField.get(player);
            Integer containerCounter = (Integer) containerCounterField.get(handle);
            Object playerConnection = playerConnectionField.get(handle);
            Object packet = openWindowPacketConstructor.newInstance(containerCounter, 0, title, inventory.getSize(), false);
            sendPacket.invoke(playerConnection, packet);
        }
        catch(Exception ex)
        {
            // Shh, I don't care about you <3
        }
    }
}