MySQL Integration

package me.bradley.TestingMySQL;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.scheduler.BukkitRunnable;

public class Core extends JavaPlugin implements Listener {

	Connection connection;

	private Core plugin;
	private String username = "sql8154449";
	private String password = "hGEl3P6H7K";

	public void onEnable() {
		getServer().getPluginManager().registerEvents(this, this);
		plugin = this;
		printData();
	}

	private void printData() {
		new BukkitRunnable() {
			@Override
			public void run() {
				openConnection();

				List<String> temp = getNameColumn("name");

				new BukkitRunnable() {
					@Override
					public void run() {
						if (!temp.isEmpty()) {
							for (String name : temp) {
								System.out.println("I found the name: " + name);
							}
						} else {
							System.out.println("There were no names :(");
						}
					}
				}.runTask(plugin);
			}
		}.runTaskAsynchronously(this);
	}

	public synchronized void openConnection() {
		try {
			connection = DriverManager.getConnection("jdbc:mysql://sql8.freemysqlhosting.net:3306/sql8154449", username,
					password);
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	public boolean containsElement(String field, String element) {
		String query = "SELECT `" + field + "` FROM `testing` WHERE `" + field + "`='" + element + "'";

		try {
			ResultSet res = connection.prepareStatement(query).executeQuery();

			boolean temp = res.next();
			res.close();
			return temp;

		} catch (SQLException e) {
			e.printStackTrace();
			return true;
		}
	}

	public void insertElement(String element, String uuid) {
		String query = "INSERT INTO `testing` (`name`, `uuid`) VALUES('" + element + "', '" + uuid + "')";
		PreparedStatement p;
		try {
			p = connection.prepareStatement(query);
			p.execute();
			p.close();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	public List<String> getNameColumn(String columnName) {
		List<String> temp = new ArrayList<String>();

		String query = "SELECT '" + columnName + "' FROM `testing`";

		try {
			ResultSet res = connection.prepareStatement(query).executeQuery();

			while (res.next()) {
				temp.add(res.getString(columnName));
			}
			res.close();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return temp;
	}

	//testing that it works :)
	@EventHandler
	public void onJoin(PlayerJoinEvent e) {
		Player player = e.getPlayer();
		if (containsElement("name", player.getName())) {
			player.sendMessage("I have you! Your UUID is: " + player.getUniqueId().toString());
			return;
		} else {
			insertElement(player.getName(), player.getUniqueId().toString());
			player.sendMessage("I didn't have you but now I do! Your UUID is: " + player.getUniqueId().toString());
			return;
		}
	}

}