Plugin load error

Hey! I've been working on a plugin simulare to the one SSundee uses in his prison server.
This plugin I am making, adds Points (simulare to SSundee's tickets) that you can use to enchant items, buy items and do quests.
I finished the plugin, and it has no errors in Eclipse, but for some reason, when I try to load it on the server, it wont load.

This is a plugin I really need to work, so any help would be much apprechiated!

Error message:

Code:

[14:31:40 ERROR]: Could not load 'plugins\Points.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: Abnormal plugin type
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.jav
a:56) ~[craftbukkit.jar:git-Bukkit-1.7.9-R0.1-10-g8688bd4-b3092jnks]
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.j
ava:127) ~[craftbukkit.jar:git-Bukkit-1.7.9-R0.1-10-g8688bd4-b3092jnks]
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.
java:328) ~[craftbukkit.jar:git-Bukkit-1.7.9-R0.1-10-g8688bd4-b3092jnks]
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager
.java:251) [craftbukkit.jar:git-Bukkit-1.7.9-R0.1-10-g8688bd4-b3092jnks]
        at org.bukkit.craftbukkit.v1_7_R3.CraftServer.loadPlugins(CraftServer.ja
va:355) [craftbukkit.jar:git-Bukkit-1.7.9-R0.1-10-g8688bd4-b3092jnks]
        at org.bukkit.craftbukkit.v1_7_R3.CraftServer.<init>(CraftServer.java:31
7) [craftbukkit.jar:git-Bukkit-1.7.9-R0.1-10-g8688bd4-b3092jnks]
        at net.minecraft.server.v1_7_R3.PlayerList.<init>(PlayerList.java:68) [c
raftbukkit.jar:git-Bukkit-1.7.9-R0.1-10-g8688bd4-b3092jnks]
        at net.minecraft.server.v1_7_R3.DedicatedPlayerList.<init>(SourceFile:14
) [craftbukkit.jar:git-Bukkit-1.7.9-R0.1-10-g8688bd4-b3092jnks]
        at net.minecraft.server.v1_7_R3.DedicatedServer.init(DedicatedServer.jav
a:126) [craftbukkit.jar:git-Bukkit-1.7.9-R0.1-10-g8688bd4-b3092jnks]
        at net.minecraft.server.v1_7_R3.MinecraftServer.run(MinecraftServer.java
:436) [craftbukkit.jar:git-Bukkit-1.7.9-R0.1-10-g8688bd4-b3092jnks]
        at net.minecraft.server.v1_7_R3.ThreadServerApplication.run(SourceFile:6
28) [craftbukkit.jar:git-Bukkit-1.7.9-R0.1-10-g8688bd4-b3092jnks]
Caused by: java.lang.InstantiationException: me.piggercast.points.Core
        at java.lang.Class.newInstance(Unknown Source) ~[?:1.7.0_51]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.jav
a:52) ~[craftbukkit.jar:git-Bukkit-1.7.9-R0.1-10-g8688bd4-b3092jnks]
        ... 10 more

Main class code (called Core):

Code:

package me.piggercast.points;
 
 
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
 
import me.piggercast.points.Aquire.Mining;
import me.piggercast.points.Shop.ClickListener;
import me.piggercast.points.Shop.ShopOpener;
 
import org.bukkit.Bukkit;
import org.bukkit.Material;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.craftbukkit.Main;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.inventory.Inventory;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.meta.ItemMeta;
import org.bukkit.plugin.java.JavaPlugin;
 
public class Core extends JavaPlugin implements Listener { 
 
    Main plugin;
    public Core(Main plugin){
        this.plugin = plugin;
    }
    @EventHandler
    public void createAccount(PlayerJoinEvent event){
        File users = new File(this.getDataFolder(), "users");
        if(!users.exists())users.mkdir();
        File playerFolder = new File(users, event.getPlayer().getName());
        if(!playerFolder.exists())playerFolder.mkdir();
        File points = new File(playerFolder, "points.info");
        if(!points.exists())points.mkdir();
    }
    public static Inventory shop(){
        Inventory inv = Bukkit.createInventory(null, 9, "Select a shop!");
        {
        ItemStack item = new ItemStack(Material.STICK);
        ItemMeta meta = item.getItemMeta();
        meta.setDisplayName("§aItem Shop");
        List<String> lore = new ArrayList<String>();
        lore.add("§5Buy InGame Items");
        meta.setLore(lore);
        item.setItemMeta(meta);
        inv.addItem(item);
        }
        {
        ItemStack item = new ItemStack(Material.EMERALD);
        ItemMeta meta = item.getItemMeta();
        meta.setDisplayName("§aMoney Shop");
        List<String> lore = new ArrayList<String>();
        lore.add("§5Buy InGame Money");
        meta.setLore(lore);
        item.setItemMeta(meta);
        inv.addItem(item);
        }
        return inv;
    }
    public static Inventory ItemShop(){
        Inventory inv = Bukkit.createInventory(null, 9, "Buy an item!");
        {
        ItemStack item = new ItemStack(Material.FURNACE);
        ItemMeta meta = item.getItemMeta();
        meta.setDisplayName("§aSmelter Pickaxe");
        List<String> lore = new ArrayList<String>();
        lore.add("§aSmelts your stuff for you!");
        lore.add("§aCosts 5k points");
        meta.setLore(lore);
        item.setItemMeta(meta);
        inv.addItem(item);
        }
        {
        ItemStack item = new ItemStack(Material.TNT);
        ItemMeta meta = item.getItemMeta();
        meta.setDisplayName("§aExplosive Pickaxe");
        List<String> lore = new ArrayList<String>();
        lore.add("§aMine with explosions!");
        lore.add("§aCosts 10k points");
        meta.setLore(lore);
        item.setItemMeta(meta);
        inv.addItem(item);
        }
        {
        ItemStack item = new ItemStack(Material.DIAMOND_PICKAXE);
        ItemMeta meta = item.getItemMeta();
        meta.setDisplayName("§aExplosive Smelter Pickaxe");
        List<String> lore = new ArrayList<String>();
        lore.add("§aMine with explosions!");
        lore.add("§aSmelts your stuff for you!");
        lore.add("§aCosts 20k points");
        meta.setLore(lore);
        item.setItemMeta(meta);
        inv.addItem(item);
        }
        return inv;
    }
    public static Inventory MoneyShop(){
        Inventory inv = Bukkit.createInventory(null, 9, "Select an ammount of money!");
        {
        ItemStack item = new ItemStack(Material.EMERALD, 1);
        ItemMeta meta = item.getItemMeta();
        meta.setDisplayName("§a1,000,000");
        List<String> lore = new ArrayList<String>();
        lore.add("§aSmelts your stuff for you!");
        lore.add("§aCosts 400 points");
        meta.setLore(lore);
        item.setItemMeta(meta);
        inv.addItem(item);
        }
        {
        ItemStack item = new ItemStack(Material.EMERALD, 10);
        ItemMeta meta = item.getItemMeta();
        meta.setDisplayName("§a10,000,000");
        List<String> lore = new ArrayList<String>();
        lore.add("§aMine with explosions!");
        lore.add("§aCosts 3500 points");
        meta.setLore(lore);
        item.setItemMeta(meta);
        inv.addItem(item);
        }
        {
        ItemStack item = new ItemStack(Material.EMERALD, 64);
        ItemMeta meta = item.getItemMeta();
        meta.setDisplayName("§a100,000,000");
        List<String> lore = new ArrayList<String>();
        lore.add("§aMine with explosions!");
        lore.add("§aCosts 38000 points");
        meta.setLore(lore);
        item.setItemMeta(meta);
        inv.addItem(item);
        }
        return inv;
    }
 
    @Override
    public void onEnable(){
     
        getServer().getPluginManager().registerEvents(new Mining(this), this);
        getServer().getPluginManager().registerEvents(new ClickListener(this), this);
        getServer().getPluginManager().registerEvents(new ShopOpener(), this);
        getServer().getPluginManager().registerEvents(this, this);
     
        File dir = new File(this.getDataFolder().getAbsolutePath());
        if(!dir.exists())dir.mkdir();
    }
    @Override
    public void onDisable(){
    }
    public static String Prefix = "§a[§6Points§a] ";
 
    @SuppressWarnings({ "unused", "resource" })
    public boolean onCommand(CommandSender sender, Command cmd, String commandLabel, String[] args){
        Player player = (Player)sender;
     
        if(commandLabel.equalsIgnoreCase("points")){
            File playerFolder = new File(this.getDataFolder() + "/users/", player.getName());
            try{
                PrintWriter pw = new PrintWriter(new FileWriter(new File(playerFolder, "points.info")), false);
                BufferedReader br = new BufferedReader(new FileReader(new File(playerFolder, "points.info")));
                String line = null;
                int currPoints =-1;
             
                while((line = br.readLine()) !=null){
                    currPoints = Integer.valueOf(line);
                    break;
                }
                player.sendMessage("§aYou have " + currPoints + "§apoints!");
            }catch(Exception e){
                e.printStackTrace();
            }         
        }
        if(commandLabel.equalsIgnoreCase("getpoints")){
            if(player.hasPermission("Points.test")){
                File playerFolder = new File(this.getDataFolder() + "/users/", player.getName());
                try{
                    PrintWriter pw = new PrintWriter(new FileWriter(new File(playerFolder, "points.info")), false);
                    BufferedReader br = new BufferedReader(new FileReader(new File(playerFolder, "points.info")));
                    String line = null;
                    int currPoints =-1;
                 
                    while((line = br.readLine()) !=null){
                        currPoints = Integer.valueOf(line);
                        break;
                    }
                    int newPoints = currPoints+10;
                    pw.println(newPoints);
                    br.close();
                    pw.close();
                }catch(Exception e){
                    e.printStackTrace();
                }
             
                player.sendMessage(Core.Prefix + "You gained §610 §apoints!");
            }else{
                player.sendMessage(Core.Prefix + "§cHow bout naw?");
            }
        }
        return false;
    }
}

 

Code:

Caused by: java.lang.InstantiationException: me.piggercast.points.Core
        at java.lang.Class.newInstance(Unknown Source) ~[?:1.7.0_51]

This part of the error is interesting. There is an error while instantiating your plugin.

I think this part of your code is causing the problem:

Code:java

 Main plugin;
public Core(Main plugin){
this.plugin = plugin;
}

edit: Which version of Bukkit API are you using?

 

JEREMSPEED
Im using CraftBukkit 1.7.9

 

Do this.plugin = plugin; inside your onEnable.