DB?

package com.triblion.spigot;

import org.bukkit.plugin.java.JavaPlugin;

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class Test extends JavaPlugin {

    private Connection connection;
    private String host, database, username, password
            private int port;

    @Override
    public void onEnable() {
        host = "localhost";
        port = 3306;
        database ="FrozenSuite";
        username = "test";
        password = "Password";
        try {
            Connect();
            Statement statement = connection.createStatement();
            ResultSet result = statement.executeQuery("SELECT * FROM Players WHERE balance = 0;");
            List<String> playersBalance = new ArrayList<String>();
            while (result.next()) {
                String name = result.getString("PlayerName");
                playersBalance.add(name);
            }
            statement.executeUpdate("INSERT INTO Players (PlayerName, balance ) VALUES ('PlayerName', 100);");
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onDisable() {

    }

    private void Connect() throws SQLException, ClassNotFoundException {
        if (connection !=null && !connection.isClosed()) {
            return;
        }

        synchronized (this) {
            if(connection !=null && !connection.isClosed()) {
                return;
            }
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection("jdbc:mysql://" + this.host + ":" + this.port + "/" + this.database, this.username, this.password);
        }
    }
}