LDAP getting the previous dn

 public static String getPreviousDN(String dn) {  
      String retString = null;  
      try {  
           DirContext DirCtx = DriverLocator.getInstance().getDirectory();  
           NameParser parser = DirCtx.getNameParser("");  
           Name resultdn = parser.parse(dn);  
           resultdn = resultdn.getPrefix(resultdn.size()-1);  
           retString = resultdn.toString();  
           DirCtx.close();  
      } catch (Exception e) {  
           //forget errors  
           //e.printStackTrace();  
           System.err.println("DAOHelper getPreviousDN unable to parse dn " + dn);  
      }  
      //debugging  
      //System.out.println("nameparsertest dn(size-2) = " + retString);  
      return retString;  
 }