Content Pane Question

Question

I've noticed that there seem to be two common ways in which a Content Pane is defined. I've included examples of each below and am interested in whether there's any reason that either might be preferable to use over the other.
Thanks very much.
EXAMPLE 1 _______________________________
public static void main(String[] args) {   
VPA vpa = new VPA();
JFrame frame = new JFrame("VPA");
frame.setContentPane(vpa.contentPanel);
public VPA() {
contentPanel = new JPanel();
EXAMPLE 2 ______________________________________
public static void main(String[] args) {     
VPA vpa = new VPA();
public class OtherClass extends JFrame {
public OtherClass() {
Container contentPane = getContentPane();
}

Answer 1

I usually create my own content pane then add it to the frame like this:
public class test extends JFrame{
    public test{
     JPanel contentPane = new JPanel();
     //add stuff to contentPane
     setContentPane(contentPane);
}When working with frames and swing, JPanel is usually your base content pane. Also, your first code example will not work, don't bother working with it. My example is closest to the second one.