Hello! Ive made a portable book enchater but when im in mutiplayer I get a weird glitch the video will show you what i mean.

 

 

 

Please help

Are you giving the item server side ?

here code to the GUI:

 

 

 package mod.gmod622.gui;

import java.util.Random;

import net.minecraft.client.Minecraft;
import net.minecraft.client.gui.GuiButton;
import net.minecraft.client.gui.GuiIngameMenu;
import net.minecraft.client.gui.GuiScreen;
import net.minecraft.enchantment.Enchantment;
import net.minecraft.enchantment.EnchantmentData;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.minecraft.util.MathHelper;
import net.minecraft.world.World;

public class GUIenchanter extends GuiScreen
{
private World worldMC;
private EntityPlayer entityP;
private Minecraft mineC;
public static double rand;
private static Random random = new Random();

public GUIenchanter(World world, EntityPlayer entityplayer, Minecraft minecraft)
{
worldMC = world;
entityP = entityplayer;
mineC = minecraft;


}

public void initGui()
{

buttonList.add(new GuiButton(0, width / 2 - 50, height / 2 - 50, 200, 20, "Random Enchanted Book (30 lvls)"));
}
protected void actionPerformed(GuiButton guiButton)
{
if(guiButton.id == 0)
{


if(entityP.experienceLevel >= 30 && entityP.inventory.hasItem(Item.book.itemID)) {
	EnchantedBook(entityP);
       entityP.experienceLevel -= 30;
      
       entityP.inventory.consumeInventoryItem(Item.book.itemID);
}else if(entityP.experienceLevel <= 30)
{
	entityP.addChatMessage("Not enough Levels.");
}else 
{
	entityP.addChatMessage("Book required");
}


}
}

@Override
public boolean doesGuiPauseGame()
{
    return false;
}

public static void EnchantedBook(EntityPlayer par3EntityPlayer)
{
             Enchantment enchantment = Enchantment.enchantmentsBookList[random.nextInt(Enchantment.enchantmentsBookList.length)];
    ItemStack itemstack = new ItemStack(Item.enchantedBook.itemID, 1, 0);
    int l = MathHelper.getRandomIntegerInRange(random, enchantment.getMinLevel(), enchantment.getMaxLevel());
   Item.enchantedBook.getEnchantedItemStack_do(itemstack, new EnchantmentData(enchantment, l));
par3EntityPlayer.inventory.addItemStackToInventory(itemstack);
}

} 

 

You have to use packets to send the changes induced by actionPerformed(args) to the server.

There are tutorials for PacketHandler and such on the wiki.