File.delete() does not work for directories on solaris

see code example below. Works for files, but not for directories.

import java.io.*;
 
// makes use of the File class
 
class deletefile {
 
        public static void main(String args[]) {
                boolean filedeleted = true;
                File Filo = new File(args[0]);
                System.out.println ("Path sep " + Filo.pathSeparator );
                filedeleted = Filo.delete ();
                System.out.println ( "filedeleted = " + filedeleted );
        }
}

$ java deletefile testfile
Path sep :
filedeleted = true
/home/kammy/testprogs/jh (kokomo)
$ ls testfile
testfile: No such file or directory

/home/kammy/testprogs/jh (kokomo)
$ java deletefile testdir2
Path sep :
filedeleted = false
/home/kammy/testprogs/jh (kokomo)
$ ls
deletefile.class fileOps.java testdir/
deletefile.java fileOpsMain.java testdir2/