Plugin error not understanding

Hey, i'm having this plugin error and i'm not finding out why and i would just to know how to fix it

ERROR:

Code:

[SEVERE] Could not pass event BlockPlaceEvent to Christmas v1.0
org.bukkit.event.EventException
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:341)
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
    at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
    at org.bukkit.craftbukkit.event.CraftEventFactory.callBlockPlaceEvent(CraftEventFactory.java:99)
    at net.minecraft.server.ItemBlock.interactWith(ItemBlock.java:78)
    at net.minecraft.server.ItemStack.placeItem(ItemStack.java:87)
    at net.minecraft.server.ItemInWorldManager.interact(ItemInWorldManager.java:392)
    at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:662)
    at net.minecraft.server.Packet15Place.handle(SourceFile:58)
    at net.minecraft.server.NetworkManager.b(NetworkManager.java:290)
    at net.minecraft.server.NetServerHandler.d(NetServerHandler.java:113)
    at net.minecraft.server.ServerConnection.b(SourceFile:39)
    at net.minecraft.server.DedicatedServerConnection.b(SourceFile:30)
    at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:595)
    at net.minecraft.server.DedicatedServer.r(DedicatedServer.java:222)
    at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:493)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:426)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:856)
Caused by: java.lang.NullPointerException
    at net.minecraft.server.ItemStack.setData(ItemStack.java:157)
    at net.minecraft.server.ItemStack.<init>(ItemStack.java:41)
    at org.bukkit.craftbukkit.inventory.CraftItemStack.<init>(CraftItemStack.java:61)
    at org.bukkit.craftbukkit.inventory.CraftItemStack.<init>(CraftItemStack.java:49)
    at org.bukkit.craftbukkit.inventory.CraftItemStack.<init>(CraftItemStack.java:27)
    at org.bukkit.craftbukkit.inventory.CraftInventory.firstPartial(CraftInventory.java:232)
    at org.bukkit.craftbukkit.inventory.CraftInventory.addItem(CraftInventory.java:258)
    at net.skydevs.src.Christmas.onBlockPlace(Christmas.java:51)
    at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:339)
    ... 18 more

CODE:

Code:

package net.skydevs.src;
 
import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.block.Block;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.block.BlockPlaceEvent;
import org.bukkit.inventory.ItemStack;
import java.util.Random;
 
public class Christmas extends JavaPlugin implements Listener {
    Random rand = new Random();
    public String ChristmasMessage;
 
    public void onEnable() { // Server Starts
        getLogger().info("Christmas Plugin has been enabled!");
        Bukkit.getServer().getPluginManager().registerEvents(this, this);
        getConfig().options().copyDefaults(true);
        saveConfig();
 
    }
 
    public void onDisable() { // Server Stops
        getLogger().info("Christmas Plugin has been disabled!");
 
    }
 
    public boolean onCommand(CommandSender sender, Command cmd, String Label,
            String[] args) {
 
        if (cmd.getName().equalsIgnoreCase("Christmas")) {
            Bukkit.broadcastMessage(ChatColor.BLACK+ "["+ ChatColor.RED+ "Christmas"+ ChatColor.BLACK+ "] "+ ChatColor.GREEN+ "Happy "+ ChatColor.RED+ "Christmas "+ ChatColor.GREEN+ "everyone! We hope you enjoy the new features we have for you!");
 
        }
 
        return false;
    }
   
    @EventHandler
    @SuppressWarnings("deprecation")
    public void onBlockPlace(BlockPlaceEvent e) {
        Block b = e.getBlockPlaced();
        if (b.getTypeId() == 56) {
            int id = 0;
            id = rand.nextInt(400);
            e.getPlayer().sendMessage(ChatColor.BLACK + "[" + ChatColor.RED + "Christmas"+ ChatColor.BLACK + "] " + ChatColor.GREEN+ "Ho! Ho! Ho! " + ChatColor.RED+ "Merry Christmas! Enjoy your gift!");
            e.getPlayer().getInventory().addItem(new ItemStack(id, 1));
            e.getPlayer().updateInventory();
            e.getPlayer().getInventory().removeItem(new ItemStack(56, 1));
            e.getPlayer().updateInventory();
            e.setCancelled(true);
        }
    }
}

Thanks!

 

which is line 157 in ItemStack.java?

 

You're giving the player an item with Id that could go as high as 400. Do blocks even go that high?

 

Yes, items follow after blocks, but there is a hole between those groups.

 

yes but not all values are used, if your code calls one that isnt used, you would get that error. what i would do is put the values you want into an array and then randomly pick an element in that array to give

 

Cant you simply do (0-143, 256-396) Not sure if you guys got any ideas but umm idk how to do that cuz it dosent work :/

 

and MAYBE just check if it is null before you do stuff. thats how NPEs are usually avoided

 

@raGan
And how can i do that?

 

This appears to be true.

Using if(whatYouWantToCheck != null) {
//do stuff
}

 

so....

if(id != null) {
bla bla
} ?

 

if(Material.getMaterial(id) == null) {
//add item
}

 

Thanks but theres just 1 problem...

If (--->Material<---.getMaterial(id) == null) {

}

...is an error... im not so sure why it should be working it worked in my other plugin so im not sure why....

 

import Material class(quick fix in Eclipe (I think Ctrl + 1))

.getMaterial() is it's static method, it should always work

 

It works!@ Is there a way to find out if the inventory is full and if it is than to do something?

 

Again with the avatars!
raGan. you sneaky bastard, I bet you secretly enjoy seeing "This post has been edited 3 times." every time someone mentions you! The money we waste every year on new edit buttons... I bet there's a pile of them out back with squeaky hinges, worn out springs and faded letters.

 

addItem returns a map of items that couldn't be added, I believe..

 

Well when i spam my diamondore on the floor it keeps going if the inventory is full... :/