Java program codes: java creating and deleting file automatically

import java.util.*;
import java.io.*;
public class ab extends TimerTask
{
static File file;
public static void main(String[] args ) throws IOException
{
file = new File ("test.dat");
if (! file.exists() )
{
file.createNewFile();
}
System.out.println("File Created");
ab test = new ab();
Timer t = new Timer ();
t.schedule(test, 30*1000L);
try
{
while (file.exists())
{
System.out.print('.');
Thread.sleep(1000);
}
}
catch (InterruptedException ie)
{
System.out.println("Error");
}
System.exit(0);
} //end of main
public void run()
{
file.delete();
}
} //end of public class ab