Centrar ventanas

    public static void setWinCenter(JFrame tFrame) {
        Dimension tScreenSize = Toolkit.getDefaultToolkit().getScreenSize();

        tFrame.setLocation(
                (int) ((tScreenSize.getWidth() - tFrame.getWidth()) / 2),
                (int) ((tScreenSize.getHeight() - tFrame.getHeight()) / 2));
    }