permissions not work correctly deleting a file

A simple java program:
public class ReadString {
   public static void main (String[] args) {
   System.out.print("Enter the path name to delete: ");
   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
   String pathName = null;
    try {
         pathName = br.readLine();
      } catch (IOException ioe) {
         System.out.println("IO error trying to read path name!");
         System.exit(1);
      }
      System.out.println("Thanks, deleting the file, " + pathName);
      File fileDaCancellare = new File(pathName);
      if(fileDaCancellare.exists()) {
       if(!fileDaCancellare.delete()) {
  System.out.println("Error trying to delete path name!");
         System.exit(1);
  }
        } else {
         // noting
        }
 }
} // end of ReadString class

Works in a strange way:
icanepa@JtLaptop1:~/local$ ls -la delme
ls: delme: Nessun file o directory
icanepa@JtLaptop1:~/local$ sudo touch delme
icanepa@JtLaptop1:~/local$ sudo chmod -w delme
icanepa@JtLaptop1:~/local$ ls -la delme
-r--r--r-- 1 root root 0 2007-11-27 17:42 delme
icanepa@JtLaptop1:~/local$ java ReadString
Enter the path name to delete: delme
Thanks, deleting the file, delme
icanepa@JtLaptop1:~/local$ ls -la delme
ls: delme: Nessun file o directory
icanepa@JtLaptop1:~/local$

A program of a simple user delete a root read only file, are permission working good?
Italo Canepa