小编rom*_*n23的帖子

我试图paint()从另一个类调用该方法,但它只是不起作用.

这是代码:

Main.java:

public class Main extends JFrame {
    private static final long serialVersionUID = 1L;

    private int WIDTH = 600;
    private int HEIGHT = 400;
    private String NAME = "Dark Ages";
    private String VERSION = "0.0.1 Pre-Alpha";
    static boolean running = false;

    private Image dbImage;
    private Graphics dbg;

    public Main() {
        //Initialize window
        JFrame frame = new JFrame();
        frame.setTitle(NAME + " - " + VERSION);
        frame.setSize(WIDTH, HEIGHT);
        frame.setVisible(true);
        frame.setResizable(false);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);

        //Running
        running = true;
    } …

我正在尝试为我的MySQL数据库创建一个注册系统.我创建了一个Java表单,用户可以在其中插入用户名,密码和电子邮件.我采用该信息并将其存储在变量中.MySQL连接代码有效,它确实插入了一个新行,但MySQL页面上的信息是空白的.我做错了吗？

public class Main extends JFrame {

private static final long serialVersionUID = 1L;

private JPanel contentPane;
private JTextField textField;
private JPasswordField passwordField;

private static Connection con;
private static PreparedStatement st;
private static int rs;

String username;
String password;
String email;
private JTextField textField_1;

String insertTableSQL = "INSERT INTO `users`" + "(username, password, email) VALUES" + "(?,?,?)";

public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                Main frame = new Main();
                frame.setVisible(true);
            } catch …