How to locate JTextField under other JTextField?

I am making authentication GUI which should contain 2 text fields, username JTextField and password JPasswordField. I want to make the password field be below the username field. my current code is as follows:

public class GuiAuthentication extends JFrame {

private static final int WIDTH  = 1000;
private static final int HEIGHT =  650;

private JTextField     tfUsername;
private JPasswordField tfPassword;

public GuiAuthentication() {
    try {
        setTitle("Metaspace Launcher");

        getContentPane().setLayout(new FlowLayout());
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        setSize(WIDTH, HEIGHT);

        tfUsername = new JTextField("Username");
        tfPassword = new JPasswordField("********");

        tfUsername.setBounds(10, 10, 50, 20);
        tfPassword.setBounds(10, 50, 50, 20);

        getContentPane().add(tfUsername);
        getContentPane().add(tfPassword);

        setPreferredSize(new Dimension(WIDTH, HEIGHT));
        setMinimumSize  (new Dimension(WIDTH, HEIGHT));
        setMaximumSize  (new Dimension(WIDTH, HEIGHT));

        setResizable(false);
        requestFocus();

        setLocationRelativeTo(null);
        setVisible(true);
    } catch (final Exception ex) {
        ex.printStackTrace();
        System.exit(ex.toString().hashCode());
    }
}

@Override
public void paint(final Graphics g) {
    super.paint(g);

    Gui.drawBackground(this, g, WIDTH, HEIGHT);
    Gui.drawRect(g, WIDTH/3, HEIGHT/3 + 20, 325, 200, 0xAA000000);
}

However, this results in the password field being located against the username field, and both of them are centered, and not located at X position 10 which I specify:

--> Screenshot (click)

Is the problem in the layout I currently use (FlowLayout)? If so, which one should I use then? If not, what else might be wrong?

Tried using GridBagLayout as well. It results in this (fields side by side, centered):