implementing the comparable interface for the type File to sort by length of the filename - comparable

Question

I would like to define a new class FileSorter that extends the type File and implements the comparable interface by defining a compareTo() to sort by the length of the filename.
public class FileSorter extends File implements Comparable<File>
{
private int size;
public FileSorter(String pathname)
{
super(pathname);
// TODO Auto-generated constructor stub
}
public int compareTo(File b)
{
if (this.length() == b.length())
return 0;
else if (this.length() > b.length())
return 1;
else
return -1;
}
}
public class FileSorterDemo {
public static void main(String[] args)
{
FileSorter directory = new FileSorter(args[0]);
FileSorter[] files = ((FileSorter) directory).listFiles();
Arrays.sort(files);
for (int i = 0; i < files.length; i++)
System.out.println(files[i].getName());
}
}

Answer 1

I got the following working solution using comparator. Is this acceptable?
Can this be implemented using Comparable Interface?
import java.io.File;
import java.util.*;
public class FileSortByFilenameLength implements Comparator<File>
{
#Override
public int compare(File arg0, File arg1) {
// TODO Auto-generated method stub
if (arg0.getName().length() > arg1.getName().length())
return 1;
else if (arg0.getName().length() < arg1.getName().length())
return -1;
else
return 0;
}
}
public class FileSorterDemo {
public static void main(String[] args)
{
File directory = new File(args[0]);
File[] files = directory.listFiles();
Arrays.sort(files, new FileSortByFilenameLength());
for (int i = 0; i < files.length; i++)
System.out.println(files[i].getName() + " - " + files[i].getName().length());
}
}