Simple Use of Extended Thread

import javax.swing.JOptionPane;
public class Xtendedthread extends Thread
{

static public void main(String ar[])
{
Xtendedthread x = new Xtendedthread();
int i = Integer.parseInt(JOptionPane.showInputDialog("Enter which table you want:\n1. 19 \n2. 24 \n 3. 17"));
switch(i)
{
case 1: x.nineteen();JOptionPane.showMessageDialog(null,"Main thread waiting for child thread..!!");break;
}
}
public void nineteen()
{
start();
}
public void run()
{
String table=" ";
for(int i=1;i<11;i++)
{
table =table+ "\n"+ 19*i;
}
JOptionPane.showMessageDialog(null,"Child thread giving result" +table);
}
}