How to stop players from dropping item with a custom display name

I am trying to stop players from dropping a custom named item, i get no errors in my code but i get an error in the console when i drop the item (It does drop through), what am i doing wrong?

Code:

[15:51:36 ERROR]: Could not pass event PlayerDropItemEvent to Helper v1.7.4
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:320) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:62) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.j
ava:481) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:466) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at net.minecraft.server.v1_7_R1.EntityHuman.a(EntityHuman.java:565) [cra
ftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at net.minecraft.server.v1_7_R1.EntityHuman.a(EntityHuman.java:517) [cra
ftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at net.minecraft.server.v1_7_R1.PlayerConnection.a(PlayerConnection.java
:494) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at net.minecraft.server.v1_7_R1.PacketPlayInBlockDig.a(SourceFile:53) [c
raftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at net.minecraft.server.v1_7_R1.PacketPlayInBlockDig.handle(SourceFile:8
) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at net.minecraft.server.v1_7_R1.NetworkManager.a(NetworkManager.java:146
) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at net.minecraft.server.v1_7_R1.ServerConnection.c(SourceFile:134) [craf
tbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at net.minecraft.server.v1_7_R1.MinecraftServer.u(MinecraftServer.java:6
55) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at net.minecraft.server.v1_7_R1.DedicatedServer.u(DedicatedServer.java:2
50) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at net.minecraft.server.v1_7_R1.MinecraftServer.t(MinecraftServer.java:5
45) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java
:457) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:6
17) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
Caused by: java.lang.NullPointerException
        at Helper.Help1.onItemDrop(Help1.java:40) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0
_45]
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.7.0
_45]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1
.7.0_45]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.7.0_45]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:318) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2978jnks]
        ... 15 more

Console error

Code:java

    @EventHandler
    public void onItemDrop(PlayerDropItemEvent e)
    {
        Player player = e.getPlayer();
        if(e.getPlayer().getItemInHand().getItemMeta().getDisplayName().equalsIgnoreCase("test"))
    {
        player.sendMessage("You cant do this bro :)");
        e.setCancelled(true);
    }
    }

 

Code:

Caused by: java.lang.NullPointerException
        at Helper.Help1.onItemDrop(Help1.java:40) ~[?:?]

There is the error, if you want more help post the full code.

 

angry_carrot64
There are lots of things that could be null here:
- ItemInHand could be null
- ItemMeta may be null
- DisplayName could be null
Make sure the ItemInHand is not null, make sure the ItemInHand hasItemMeta(), and make sure it hasDisplayName as well.

 

would this work? xTrollxDudex

Code:java

@EventHandler
    public void onItemDrop(PlayerDropItemEvent e)
    {
        Player player = e.getPlayer();
        if(e.getPlayer().getItemInHand().hasItemMeta()) return;
        if(e.getPlayer().getItemInHand().getItemMeta().hasDisplayName()) return;
        if(e.getPlayer().getItemInHand().getItemMeta().getDisplayName().equalsIgnoreCase("Test"))
    {
        player.sendMessage("You cant do this bro :)");
        e.setCancelled(true);
    }
    }

nuno1212sss

Code:java

package Helper;
 
import java.util.List;
 
import net.minecraft.server.v1_7_R1.Item;
 
import org.bukkit.event.player.PlayerDropItemEvent;
import org.bukkit.entity.Player;
import org.bukkit.event.Event;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.entity.EntityDeathEvent;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.meta.ItemMeta;
import org.bukkit.event.EventHandler;
 
 
public class Help1 implements Listener
{
    @EventHandler
    public void onDeath(EntityDeathEvent event){
    if(!(event.getEntity() instanceof Player)) return;
    Player player = (Player) event.getEntity();
    List<ItemStack> drops = event.getDrops();
    for(ItemStack item:drops){
    if(!(item.hasItemMeta())) return;
    ItemMeta meta = item.getItemMeta();
    if(!(meta.hasDisplayName())) return;
    if(!(meta.getDisplayName().equalsIgnoreCase("Test"))) return;
    {
    drops.remove(item);
    }
    }
    }
 
    @EventHandler
    public void onItemDrop(PlayerDropItemEvent e)
    {
        Player player = e.getPlayer();
        if(e.getPlayer().getItemInHand().hasItemMeta()) return;
        if(e.getPlayer().getItemInHand().getItemMeta().hasDisplayName()) return;
        if(e.getPlayer().getItemInHand().getItemMeta().getDisplayName().equalsIgnoreCase("Test"))
    {
        player.sendMessage("You cant do this bro :)");
        e.setCancelled(true);
    }
    }
 
 
    //if(e.getItemDrop().getItemStack().getItemMeta().hasDisplayName()) return;
}

 

Code:java

if(player.getItemInHand().getItemMeta() != null){
    if(player.getItemInHand().getItemMeta().getDisplayName() != null){
        if(player.getItemInHand().getItemMeta().getDisplayName().equals("Test")){

It's something like this i believe, I also think you can remove one of these lines, i just can't remember which. Good luck!

 

angry_carrot64
You forgot to check if the iteminhand was null.

 

if(itemInHand != null && itemInHand.hasItemMeta && hasDisplayName)
do something

 

reider45 with that code i no longer get an error but the item can still be droped

Code:java

    @EventHandler
    public void onItemDrop(PlayerDropItemEvent e)
    {
        Player player = e.getPlayer();
        if(player.getItemInHand() != null) return;
        if(player.getItemInHand().getItemMeta() != null) return;
            if(player.getItemInHand().getItemMeta().getDisplayName() != null) return;
                if(player.getItemInHand().getItemMeta().getDisplayName().equals("Test"))
 
    {
        player.sendMessage("You cant do this bro :)");
        e.setCancelled(true);
    }
    }

 

Try using this

Code:java

  @EventHandler
    public void onItemDrop(PlayerDropItemEvent e)
    {
        Player player = e.getPlayer();
        if(player.getItemInHand() != null){
        if(player.getItemInHand().getItemMeta() != null){
            if(player.getItemInHand().getItemMeta().getDisplayName() != null){
                if(player.getItemInHand().getItemMeta().getDisplayName().equals("Test"))
 
    {
        player.sendMessage("You cant do this bro :)");
        e.setCancelled(true);
    }
 }
 }
 }
    }

 

reider45 Didnt work nothing shows up in the console but it still allows it to be dropped with the q button

 

I would use a config:

Code:java

public class AntiDropListener implements Listener{
 
    File file = new File("plugins/DropStop", "DropBlacklist.yml");
    FileConfiguration blacklist = YamlConfiguration.loadConfiguration(file);
 
    @SuppressWarnings("deprecation")
    @EventHandler(priority = EventPriority.HIGHEST)
    public void onDrop (PlayerDropItemEvent e) {
 
 
        int dropid = e.getItemDrop().getItemStack().getTypeId();
 
        if(blacklist.getIntegerList("DropBlacklist").contains(dropid)) {
            if(e.getPlayer().isOp()) {
                return;
 
            }
            else
            e.setCancelled(true);
        }
 
    }
 
 
}

 

Why is everybody troubling around with the deprecated Magic-Values?
Just write the getType()-Material.name() into the Config and check it per Material.getMaterial(String name);