private void readPrefixes() {
        ldaps = new ArrayList<Ldap>();
        try {
            Scanner scan = new Scanner(new File(PREFIX_FILE));
            while (scan.hasNext()) {
                String prefix = scan.nextLine();
                Ldap ldap = new Ldap(prefix);
                ldaps.add(ldap);
            }
        } catch (FileNotFoundException ex) {
            System.err.println("ERROR: file not found " + PREFIX_FILE);
        }
    }