java swing GUI basic... separate thread for event ...

package gui.basics;

import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;

public class GUi2 extends JFrame {

private JLabel l1, l2;
private JTextField t1, t2;
private JButton b1, b2;



public GUi2()
{
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
l1 = new JLabel("var1");
l2 =new JLabel("var2");
t1 =new JTextField(10);
t2 =new JTextField(10);
b1 =new JButton("Ok");
b2 =new JButton("cancel");

//GridLayout gl =new GridLayout(2,3);
FlowLayout fl =new FlowLayout();
Container c = getContentPane();
c.setLayout(fl);
c.add(l1);
c.add(t1);
c.add(l2);
c.add(t2);
c.add(b1);
c.add(b2);
PQR obj =new PQR();
b1.addActionListener(obj);
b2.addActionListener(obj);
//setSize(300,400);
pack();
System.out.println("gui building " + Thread.currentThread());;


setTitle("sample window");
setVisible(true);

}

 class PQR implements ActionListener
 {
 
class StartThread extends Thread
{
public StartThread() { start(); }
public void run() { doRegistration(); }
 
 
}

public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub

System.out.println("gui building " + Thread.currentThread());;
if(arg0.getSource() == b1)
{
System.out.println("hello");
StartThread t = new StartThread();


}
else if(arg0.getSource() == b2)
{
System.out.println("hi");
}

}
 }



private void doRegistration() {
// TODO Auto-generated method stub
try {
Thread.sleep(10000000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}


}

}