Java runtime not working

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

public class SwingFrame
{
public static void main(String[] args) throws Exception
{
SwingFrame1 sf=new SwingFrame1();
}
public SwingFrame(){
JFrame f = new JFrame("Frame in Java Swing");
f.getContentPane().setLayout(null);
JLabel lbl1 = new JLabel("Name");
JTextField jt1=new JTextField(15);
JLabel lbl2 = new JLabel("Age");
JTextField jt2=new JTextField(15);
JLabel lbl3 = new JLabel("Gender");
final JTextField txt=new JTextField(15);
JRadioButton Male,Female;
ButtonGroup radioGroup=new ButtonGroup();
Male=new JRadioButton("Male");
radioGroup.add(Male);
Female=new JRadioButton("Female");
radioGroup.add(Female);
JLabel lbl4=new JLabel("Branch");
final JComboBox jc=new JComboBox();
jc.addItem("Select");
jc.addItem("MCA");
jc.addItem("MBA");
jc.addItem("BE");
jc.addItem("BTech");
jc.addItem("Others");
lbl1.setBounds(100,120,70,30);
lbl2.setBounds(100,240,70,30);
lbl3.setBounds(100,340,70,30);
lbl4.setBounds(100,420,70,30);
jt1.setBounds(170,120,100,40);
jt2.setBounds(170,230,100,40);
Male.setBounds(170,340,100,40);
Female.setBounds(270,340,100,40);
jc.setBounds(170,420,100,40);
txt.setBounds(290,420,200,40);
jc.addItemListener(new ItemListener(){
public void itemStateChanged(ItemEvent e){
if(e.getSource() == jc) {
if(jc.getSelectedItem().equals("Others")){
txt.setVisible(true);
}
else{
txt.setVisible(false);
}

}
}
});
f.add(lbl1);
f.add(lbl2);
f.add(lbl3);
f.add(lbl4);
f.add(jt1);
f.add(jt2);
f.add(jc);
f.add(Male);
f.add(Female);
f.add(txt);
txt.setVisible(false);
f.setSize(1000,1000);
f.setVisible(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
The above program not running please check it and reply..