JavaInvalid value for getInt()

Question

I try to make a script for bukkit. It needs to go up 1 in the mysql table if it kills a zombie. Whats wrong? or is there maybe another method?

Error: java.sql.SQLException: Invalid value for getInt() - 'CraftZombie'

        PreparedStatement kills = connection.prepareStatement("SELECT ? FROM `data` WHERE name=?");
        kills.setString(1,entity.toString());
        kills.setString(2,name);
        ResultSet result = kills.executeQuery();


        String entity_string = entity.toString();

        result.next();
        //int score = 1;
        //score = result.getInt(1);
        //Integer score2 = (Integer) result.getObject(entity_string);

        int SC = result.getInt(entity_string);



        PreparedStatement stat = connection.prepareStatement("UPDATE data SET ?=? WHERE name=?",
                ResultSet.TYPE_FORWARD_ONLY,
                ResultSet.CONCUR_UPDATABLE);
        stat.setString(1,entity.toString());
        stat.setInt(2, SC + 1);
        stat.setString(3,name);

Answer 1

First of all, don't do mysql query in the event, that make the server lag.

You have to create hashmap with the data you want to link to mysql server and do a scheduler Async task that do the query.

Example:

package test;

import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Map.Entry;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;

import org.bukkit.entity.Player;
import org.bukkit.entity.Zombie;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.entity.EntityDeathEvent;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.scheduler.BukkitRunnable;

import com.mysql.jdbc.Connection;

public class Event extends JavaPlugin implements Listener {

    // Mysql update data
    public static ConcurrentHashMap<UUID, Integer> player_zombiekills = new ConcurrentHashMap<UUID, Integer>();

    // Mysql connection data
    public static Connection connection;
    private String host = "localhost";
    private String database = "DB";
    private String username = "user";
    private String password = "123";
    private int port = 3306;

    //Kill zombie event
    @EventHandler
    public void zombieDeath(EntityDeathEvent eve) {
        if (!(eve.getEntity() instanceof Zombie)) return; // Stop if death is not zombie
        if (!(eve.getEntity().getKiller() instanceof Player)) return; // Stop if killer is not player
        UUID uid = eve.getEntity().getKiller().getUniqueId(); // Save player uuid
        if (player_zombiekills.contains(uid)) player_zombiekills.put(uid, 0); // Set kills 0 if not exist in hashmap
        player_zombiekills.put(uid, player_zombiekills.get(uid) + 1); // plus 1 kills value
    }

    //On enable connection
    public void onEnable() {
        try {
            if (connection != null && !connection.isClosed()) return;
            Class.forName("com.mysql.jdbc.Driver");
            connection = (Connection) DriverManager.getConnection("jdbc:mysql://" + host + ":" + port + "/" + database, username, password);
            if (!connection.isClosed()) System.out.println("[MySQL] " + "Connected to '" + database + "'");
        } catch (Exception e) {
            System.err.println("[MySQL] " + e.getMessage());
        }

        new BukkitRunnable() {
            public void run() {
                // for updates
                for (Entry<UUID, Integer> ent : player_zombiekills.entrySet()) {
                    try {
                        // send update
                        connection.createStatement().executeUpdate("UPDATE `tablename` SET `zombiekills`=`zombiekills`+" + ent.getValue() + " WHERE `uuid`='" + ent.getKey().toString() + "'");
                        // Sucess remove entry from hashmap to reset kills
                        player_zombiekills.remove(ent.getKey());
                    } catch (SQLException e) { // If error
                        System.err.println("[MySQL] " + e.getMessage()); // Print error in console
                    }
                }
            }
        }.runTaskTimerAsynchronously(this, 20, 20 * 60 * 10); // Run async loop every 10 minutes
    }
}