我想要显示来自数据库JAVA Jframe的用户名

import javax.swing.*;
import java.sql.*;

public class MainFrame extends JFrame {
    private JLabel usernameLabel;

    public MainFrame() {
        // 初始化JFrame和其他组件
        // ...

        // 连接数据库
        Connection connection = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/mydatabase";
            String username = "root";
            String password = "password";
            connection = DriverManager.getConnection(url, username, password);

            // 查询用户名
            String query = "SELECT username FROM users";
            Statement statement = connection.createStatement();
            ResultSet resultSet = statement.executeQuery(query);
            if (resultSet.next()) {
                String username = resultSet.getString("username");
                usernameLabel.setText(username);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            // 关闭数据库连接
            if (connection != null) {
                try {
                    connection.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            MainFrame frame = new MainFrame();
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.pack();
            frame.setVisible(true);
        });
    }
}