I get an error about:

 

Attempted to load class net/minecraft/client/gui/GuiScreen for invalid side SERVER

 

I'm confuse while its happening, it's crashing on launch, not even when I use the item, I don't understand clearly why this happens.

 

package com.mramericanmike.bqt.items;

import net.minecraft.client.Minecraft;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.minecraft.util.ActionResult;
import net.minecraft.util.EnumActionResult;
import net.minecraft.util.EnumHand;
import net.minecraft.world.World;
import betterquesting.client.gui.GuiHome;
import betterquesting.core.BetterQuesting;

import com.mramericanmike.bqt.ModInfo;

public class BQTItem extends Item {

public BQTItem(String name){

	this.maxStackSize = 1;
	this.setUnlocalizedName(ModInfo.MODID + ":" + name);
	this.setRegistryName(name);
	this.setCreativeTab(BetterQuesting.tabQuesting);

}


public ActionResult<ItemStack> onItemRightClick(ItemStack itemStack, World world, EntityPlayer player, EnumHand hand)
    {
	if(world.isRemote)
    	{
    		Minecraft mc = Minecraft.getMinecraft();
		mc.displayGuiScreen(new GuiHome(mc.currentScreen));
    	}

        return new ActionResult(EnumActionResult.PASS, itemStack);
    }

}

 

If I comment the line mc.displayGuiScreen(new GuiHome(mc.currentScreen)); server launchs, but I'm confuse on why this in happening or how to fix it.

Sorry that I answer myself, but playing around and looking at some code out there, I found out that:

 

	@SideOnly(Side.CLIENT)
public ActionResult<ItemStack> onItemRightClick(ItemStack itemStack, World world, EntityPlayer player, EnumHand hand)
    {
    		Minecraft mc = Minecraft.getMinecraft();
		mc.displayGuiScreen(new GuiHome(mc.currentScreen));
    			
        return new ActionResult(EnumActionResult.PASS, itemStack);
    }

 

@SideOnly(Side.CLIENT) fixes the problem but....... Am  supposed to use that? I have heard that shouldn't be used, so I believe I'm still doing something wrng somewhere.

Sorry that = answer myself, but playing around and looking at some code out there, I found out that:

 

	@SideOnly(Side.CLIENT)
public ActionResult<ItemStack> onItemRightClick(ItemStack itemStack, World world, EntityPlayer player, EnumHand hand)
    {
    		Minecraft mc = Minecraft.getMinecraft();
		mc.displayGuiScreen(new GuiHome(mc.currentScreen));
    			
        return new ActionResult(EnumActionResult.PASS, itemStack);
    }

 

@SideOnly(Side.CLIENT) fixes the problem but....... Am  supposed to use that? I have heard that shouldn't be used, so I believe I'm still doing something wrng somewhere.

You are fine to do that. As in it will not crash the game, but be aware that the server will default back to the super.

http://www.minecraftforge.net/forum/index.php?topic=22764.0

 

You should be using a GUIHandler instead.