Jframe not loading at run time

Question

I am creating a Jframe to fetch the details from the user which has certain questions and all the answers in form of radio button. It doesot give any error at compile time. but the container is blank during runtime. I am using box class and buttongroup. here is the sample code. Please advise.
import java.util.*;
import java.awt.*;
import java.awt.event.ActionListener.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.*;
import javax.swing.border.*;
import java.applet.*;
public class exam extends JFrame
public static void main(String[] args)
JFrame.setDefaultLookAndFeelDecorated(true);
JFrame frame = new JFrame("NPDT");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container content = frame.getContentPane();
frame.setSize(800,800);
ButtonGroup group = new ButtonGroup();
ButtonGroup group1 = new ButtonGroup();
ButtonGroup group2 = new ButtonGroup();
JLabel businesslabel = new JLabel("1. What type of business are you in?");
Box vbox = Box.createVerticalBox();
vbox.add(businesslabel);
vbox.add(Box.createVerticalStrut(5));
JRadioButton edurb= new JRadioButton("Education");
JRadioButton financerb= new JRadioButton("Financial");
JRadioButton healthrb= new JRadioButton("Health Care");
JRadioButton mediarb= new JRadioButton("Media");
JRadioButton otherrb= new JRadioButton("Other");
group.add(edurb);
group.add(financerb);
group.add(healthrb);
group.add(mediarb);
group.add(otherrb);
vbox.add(edurb);
vbox.add(financerb);
vbox.add(healthrb);
vbox.add(mediarb);
vbox.add(otherrb);
JLabel branchlabel = new JLabel("2. Do you have more than one branch?");
Box vbox1 = Box.createVerticalBox();
vbox1.add(branchlabel);
vbox1.add(Box.createVerticalStrut(5));
JRadioButton yesrb= new JRadioButton("Yes");
JRadioButton norb= new JRadioButton("No");
group1.add(yesrb);
group1.add(norb);
vbox1.add(yesrb);
vbox1.add(norb);
JLabel growthlabel = new JLabel("3. What is the percentage of expected growth?");
Box vbox2 = Box.createVerticalBox();
vbox2.add(growthlabel);
vbox2.add(Box.createVerticalStrut(5));
JRadioButton lessrb= new JRadioButton("< 30");
JRadioButton medrb= new JRadioButton("31 - 50");
JRadioButton morerb= new JRadioButton("51 - 60");
JRadioButton greatrb= new JRadioButton(">60");
group2.add(lessrb);
group2.add(medrb);
group2.add(morerb);
group2.add(greatrb);
vbox2.add(lessrb);
vbox2.add(medrb);
vbox2.add(morerb);
vbox2.add(greatrb);
Box finalbox=Box.createVerticalBox();
finalbox.add(vbox(Box.createVerticalStrut(50)));
finalbox.add(vbox1(Box.createVerticalStrut(50)));
finalbox.add(vbox2(Box.createVerticalStrut(50)));
content.add(finalbox, BorderLayout.CENTER);
frame.setVisible(true);
}

Answer 1

It doesot give any error at compile time.it did for me, but after fix it displayed OK when run (java 1.5.0_05)