eroare

package me.wafflemaster.com;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.logging.Logger;

import org.bukkit.ChatColor;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;
import org.bukkit.plugin.PluginDescriptionFile;
import org.bukkit.plugin.java.JavaPlugin;

public class main extends JavaPlugin{
	public final Logger logger = Logger.getLogger("Minecraft");
	public static main plugin;

	@Override
	public void onDisable() {
		PluginDescriptionFile pdfFile = this.getDescription();
		this.logger.info(pdfFile.getName() + " s-a dezactivat!");
		closeConnection();
	}

	@Override
	public void onEnable() {
		PluginDescriptionFile pdfFile = this.getDescription();
		this.logger.info(pdfFile.getName() + " versiunea " + pdfFile.getVersion() + " s-a activat!");
		openConnection();
		createTable();
	}

	public boolean onCommand(CommandSender sender, Command cmd, String commandLabel, String[] args) {
		Player player = (Player) sender;
		if(commandLabel.equalsIgnoreCase("arena")) {
			if(args.length == 0){
				player.sendMessage("Foloseste /arena join");
				return true;
			}
			if(player instanceof Player){
				if(args[0].equalsIgnoreCase("join")) {
					addPlayer(player);
					return true;
				}
			}else{
				logger.info("Aceasta comanda poate fi rulata doar de jucatori!");
			}
		}
		return true;
	}

	private static Connection connection;
	static String table = "event1";

	public static void openConnection() {
		try
		{
			connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/ArenaEvent", "root", "");
		}
		catch(Exception e)
		{
			e.printStackTrace();
		}
	}

	public static void closeConnection() {
		try
		{
			connection.close();
		}
		catch(Exception e)
		{
			e.printStackTrace();
		}
	}

	public static void createTable() {
	    try{
	        PreparedStatement sql = connection.prepareStatement("CREATE TABLE IF NOT EXISTS " + table + " (ID INT(11) NOT NULL AUTO_INCREMENT, USERNAME VARCHAR(17), primary key (ID));");
	        sql.execute();
	        sql.close();
	    }catch (Exception e){
	        e.printStackTrace();
	    }
	}

	public void addPlayer(Player player) {
		if(checkPlayer(player) == false){
			try{
				PreparedStatement sql = connection.prepareStatement("INSERT INTO `" + table + "` VALUES('null'," + player.getName() + ");");
				sql.execute();
				sql.close();
			}catch (Exception e){
				e.printStackTrace();
			}
		}else{
			player.sendMessage(ChatColor.RED + "Esti deja inscris!");
		}
	}

	public boolean checkPlayer(Player player){
		try{
			PreparedStatement sql = connection.prepareStatement("SELECT * FROM `" + table + "` WHERE USERNAME=?;");
			sql.setString(1, player.getName());
			ResultSet resultSet = sql.executeQuery();
			boolean containsPlayer = resultSet.next();

			sql.close();
			resultSet.close();

			if(containsPlayer){
				return true;
			}else{
				return false;
			}
		} catch(Exception e){
			e.printStackTrace();
			return true;
		}
	}
}