null pointer exception in gridbag need help

[payal sharma]

I am getting null pointer exception in my code by using panel in place of contentPane.I need help whether this is right way to design form and write code.I also want to add scrollPanes here.Please help me as some here are experience programmer.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

public class FormA extends JFrame{
public FormA(){
setTitle("FormA");
setSize(700,500);
addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
System.exit(0);
}
});
JPanel p=new JPanel();

Container contentPane=getContentPane();
GridBagLayout gb=new GridBagLayout();

contentPane.setLayout(gb);
 

JLabel  slabel=new JLabel("Site Code(1-7)");
sfield=new JTextField(1);
JLabel snlabel=new JLabel("Serial Number ");
snfield=new JTextField(3);

[deekasha gunwant]

Hi payal,
can u mention the line that is giving exception.
regards
deekasha

[payal sharma]

I find the problem.I was using JLabel declaration two times so it was giving problem.I cwas not able to paste whole of my code as it is very very long.
payal