Making it so players can only put a certain item into a certain inventory slot.

Hey, I was wondering if there was a way to make it so players can put ONLY golden nuggets(or nothing) into slot 9(top-left), so that if someone tries to put something that isn't a golden nugget into slot 9 then it doesn't let them.

 

@morrnd
Have a look at these events.

 

@AlvinB
I'm new to this, so I can't get it to work(I've registered it).

Code:

package net.rodamar.amulets;

import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.inventory.InventoryClickEvent;

public class SlotNineAttempt implements Listener {
   
    @EventHandler
    public void SlotNineAttempt(InventoryClickEvent e) {
        Player player = (Player) e.getWhoClicked();
        int slot = e.getSlot();
        if (slot == 9) {
            player.sendMessage("Slot 9");
        }
    }
   
}

 

check if the item type is not a gold nugget, and if the slot is 9. then cancel the event

 

By the way, slots start with 0

 

Yeah, I know how the slots work.

---

I can put only golden nuggets in now, but I can't take anything out.

Code:

package net.rodamar.amulets;

import org.bukkit.ChatColor;
import org.bukkit.Material;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.inventory.InventoryClickEvent;
import org.bukkit.inventory.ItemStack;

public class SlotNineAttempt implements Listener {
   
   @EventHandler
   public void SlotNineAttempt(InventoryClickEvent e) {
     Player player = (Player) e.getWhoClicked();
     int slot = e.getSlot();
     ItemStack material = e.getCurrentItem();
     ItemStack gNug = new ItemStack(Material.GOLD_NUGGET, 1);
     ItemStack air = new ItemStack(Material.AIR);
     if (slot == 9 & !(material == gNug || material == air)) {
       player.sendMessage(ChatColor.AQUA + "This is not a valid amulet.");
       e.setCancelled(true);
     }
   }
   
}

 

@morrnd Why aren't you just comparing Material's rather than ItemStack? Also use != rather than !Object == Object
Also, check before casting

 

I'm using item stacks because it said it needed an itemStack, not a Material(which it was before). (It said "Incompatible operand types ItemStack and Material")

Okay, so the code is:

Code:

package net.rodamar.amulets;

import org.bukkit.ChatColor;
import org.bukkit.Material;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.inventory.InventoryClickEvent;
import org.bukkit.inventory.ItemStack;

public class SlotNineAttempt implements Listener {
  
    @EventHandler
    public void SlotNineAttempt(InventoryClickEvent e) {
        Player player = (Player) e.getWhoClicked();
        int slot = e.getSlot();
        ItemStack material = e.getCurrentItem();
        ItemStack gNug = new ItemStack(Material.GOLD_NUGGET, 1);
        if (slot == 9 & material != gNug) {
            player.sendMessage(ChatColor.AQUA + "This is not a valid amulet.");
            e.setCancelled(true);
        }
    }
  
}

It's letting me move anything anywhere, but nothing can go into 9.

 

@morrnd You are checking memory location. Check material rather than itemstack or use .equals

https://stackoverflow.com/questions/7520432/what-is-the-difference-between-vs-equals-in-java

 

@morrnd

Code:

if (slot == 9 && material != gNug)

You cannot compare objects using == and != operators. Use .equals() instead. == compares memory locations, while .equals() compares the actual values. The implications of this is that only primitives and enums can be compared with ==, because they always reference the same memory values.

 

I mean everything including a golden nugget doesn't go into slot 9.

@AlvinB
Also, unless I'm doing it wrong, .equals() isn't fixing it.

Code:

package net.rodamar.amulets;

import org.bukkit.ChatColor;
import org.bukkit.Material;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.inventory.InventoryClickEvent;
import org.bukkit.inventory.ItemStack;

public class SlotNineAttempt implements Listener {
   
    @EventHandler
    public void SlotNineAttempt(InventoryClickEvent e) {
        Player player = (Player) e.getWhoClicked();
        int slot = e.getSlot();
        ItemStack material = e.getCurrentItem();
        ItemStack gNug = new ItemStack(Material.GOLD_NUGGET, 1);
        if (slot == 9 & !(material.equals(gNug))) {
            player.sendMessage(ChatColor.AQUA + "This is not a valid amulet.");
            e.setCancelled(true);
        }
    }
   
}

 

@morrnd
You need two &'s in you if statement. A single & compares bitwise, which is something completely different.

 

Same issue occurs.

 

@morrnd
Can you post thecode?

 

Code:

package net.rodamar.amulets;

import org.bukkit.ChatColor;
import org.bukkit.Material;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.inventory.InventoryClickEvent;
import org.bukkit.inventory.ItemStack;

public class SlotNineAttempt implements Listener {
  
   @EventHandler
   public void SlotNineAttempt(InventoryClickEvent e) {
     Player player = (Player) e.getWhoClicked();
     int slot = e.getSlot();
     ItemStack material = e.getCurrentItem();
     ItemStack gNug = new ItemStack(Material.GOLD_NUGGET, 1);
     if (slot == 9 && !(material.equals(gNug))) {
       player.sendMessage(ChatColor.AQUA + "This is not a valid amulet.");
       e.setCancelled(true);
     }
   }
  
}

 

@morrnd
You would only be able to put in 1 gold nugget with this code. Anyways, instead of using you current approach, I'd recommend comparing ItemStack.getType().

 

@morrnd

I think everyone here forgot that .equals compares if every single value is the same. This includes item stack amounts, name, lore, and durability. I'm assuming you want it where a player can put any amount of gold nuggets in that slot. To do so, use Itemstack#isSimilar() to test if two itemstacks are similar, not exactly the same.

 

Or, just compare the Material.

 

Still isn't working. Also, how I want it to work is I want each player to put only one amulet on and for it to buff them accordingly(the 'lore' dictates what buff a player gets).

Code:

package net.rodamar.amulets;

import org.bukkit.ChatColor;
import org.bukkit.Material;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.inventory.InventoryClickEvent;
import org.bukkit.inventory.ItemStack;

public class SlotNineAttempt implements Listener {

   @EventHandler
   public void SlotNineAttempt(InventoryClickEvent e) {
     Player player = (Player) e.getWhoClicked();
     int slot = e.getSlot();
     ItemStack material = e.getCurrentItem();
     ItemStack gNug = new ItemStack(Material.GOLD_NUGGET, 1);
     if (slot == 9 && !(material.isSimilar(gNug))) {
         player.sendMessage(ChatColor.AQUA + "This is not a valid amulet.");
         e.setCancelled(true);
     }
   }

}

I tried with them materials, didn't work:

Code:

package net.rodamar.amulets;

import org.bukkit.ChatColor;
import org.bukkit.Material;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.inventory.InventoryClickEvent;
import org.bukkit.inventory.ItemStack;

public class SlotNineAttempt implements Listener {

   @EventHandler
   public void SlotNineAttempt(InventoryClickEvent e) {
     Player player = (Player) e.getWhoClicked();
     int slot = e.getSlot();
     ItemStack materialItemStack = e.getCurrentItem();
     Material material = materialItemStack.getType();
     Material gNug = Material.GOLD_NUGGET;
     if (slot == 9 && !(material.equals(gNug))) {
         player.sendMessage(ChatColor.AQUA + "This is not a valid amulet.");
         e.setCancelled(true);
     }
   }

}

 

@morrnd I'd suggest you do what @AlvinB said and compare the material instead of checking whether both items are similar or not, to get the material change the variable 'material's type to Material and use e.getCurrentItem().getType()
Then you can do material.equals(Material.GOLD). Also, make sure the slot you're putting the gold in is slot 10, as slots start at 0. So slot 9 should be top left inventory slot.

Also, are you registering your listener class?

 

@morrnd
Has your "amulet" any display name or lore? If yes, it will NOT BE SIMILAR to a plain old item stack.
Just check if "material#getType() != Material.GOLD_NUGGET".

 

I already stated that I want it to be slot 9, and I just tried that(I just edited the previous post before I saw your post).

Yeah, it has lore, so I just tested it as a material and it doesn't work - see my last post.

 

You dont need to create all those variables if you just need them once. It makes your code less readable. Just do e.getCurrentItem.getType.equals(Material.GOLD_NUGGET)

 

@Lordloss *getType() == Material.GOLD_NUGGET

 

@morrnd
Do you want to get e.getCursor() and not e.getCurrentItem() by any chance?

 

@bwfcwalshy youre right, i still prefer equals for enums.