Action

package com.company;

import javax.swing.*;

public class Main {

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setBounds(128, 128, 800, 600);
        frame.setTitle("Hello");
        frame.setVisible(true);

        frame.setFocusable(true);
        frame.getContentPane().add(new Panel());
    }

    public void action() {
        Connection connect;

        try {
            Class.forName("com.mysql.jdbc.Driver");

            String serverName = "localhost",
                    databaseName = "it-learning",
                    url  = "jdbc:mysql://" + serverName + "/" + databaseName,
                    user = "root",
                    password = "";

            connect = DriverManager.getConnection(url, user, password);
            int id = (int)(Math.random() * 21) + 1;
            String query = "SELECT * FROM table WHERE id = " + id;
            Statement statement = connect.createStatement();
            ResultSet set = statement.executeQuery(query);

            while (set.next())
                textField.setText(set.getString("text"));

            connect.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}