Assistance needed on this code, please

Question

The code below is an example program:
/* package demo.swing; */
import javax.swing.JFrame;
* Hello World application
* @author MAbernethy
public class HelloWorld extends JFrame
     private javax.swing.JLabel jLabel = null;
     private javax.swing.JTextField jTextField = null;
     private javax.swing.JButton jButton = null;
     public static void main(String[] args)
          HelloWorld w = new HelloWorld();
          w.setVisible(true);
     public HelloWorld()
          super();
          this.setSize(300, 200);
          this.getContentPane().setLayout(null);
          this.add(getJLabel(), null);
          this.add(getJTextField(), null);
          this.add(getJButton(), null);
          this.setTitle("Hello World");
     private javax.swing.JLabel getJLabel() {
          if(jLabel == null) {
               jLabel = new javax.swing.JLabel();
               jLabel.setBounds(34, 49, 53, 18);
               jLabel.setText("Name:");
          return jLabel;
     private javax.swing.JTextField getJTextField() {
          if(jTextField == null) {
               jTextField = new javax.swing.JTextField();
               jTextField.setBounds(96, 49, 160, 20);
          return jTextField;
     private javax.swing.JButton getJButton() {
          if(jButton == null) {
               jButton = new javax.swing.JButton();
               jButton.setBounds(103, 110, 71, 27);
               jButton.setText("OK");
          return jButton;
The code compiles without any probems,but when run the following error messsages appear:
Exception in thread "main" java.lang.Error: Donot use HelloWorld.add() use HelloWorld.getContentPane().add() instead
at javax.swing.Jframe.creatRootPaneException(Jframe.java:465)
at javax.swing.Jframe.addImpl(Jframe.java:491)
at java.awt.Container.add(Container.java:518)
at HelloWorld.<init>(HelloWorld.java:26)
at HelloWorld.main(HelloWorld.java:17)

Answer 1

Donot use HelloWorld.add() use
HelloWorld.getContentPane().add() instead
Isn't that obvious enough?D'oh! That was pretty obvious... ;)Yup, but my comment was directed at the OP, and I wish he reads your answer and remembers it next time. :)