Sorting XML response based on more than one field - Web Experience Factory (Portlet Factory)

I was facing a problem to sort xml response based on more than one field.
Tried to use Transform Sort Builder but unable to implement it.
Finally implemented a solution of writing my custom comparator to sort the XML response.

My Sample XML Response :

<?xml version="1.0" encoding="utf-8"?>

<Invoices>

  <Invoice>

    <Date>06/10/2013 16:14:26</Date>

    <InvoiceId>str1234</InvoiceId>

    <Client>str1234</Client>

    <BillingEntity>str1234</BillingEntity>

    <UserAccess>str1234</UserAccess>

    <Reports>

      <Report>str1234</Report>

    </Reports>

  </Invoice>

</Invoices>

// Sort Method

public  IXml sort(WebAppAccess webAppAccess, IXml sourceData) {

       System.out.println("!!!!!!In SortInvioceReportLJO.sort 111111111!!!!!!!!!!!!!!");

         IXml result = sourceData.cloneElement();

        IXml parent = result;

        // find the elements to be sorted

        List elements = XmlUtil.findElements(parent, "Invoices/Invoice");

        // loop through each element to be sorted

        Iterator iterator = elements.iterator();

        while (iterator.hasNext()) {

            IXml element = (IXml)iterator.next();

            // remove the element from its parent element

            parent.removeChildElement(element);

        }

        // sort the list of elements

       System.out.println("!!!!!!In SortInvioceReportLJO.Collection Sort!!!!!!!!!!!!!!");

        Collections.sort(elements, new CustomComparator());

        // loop through each element again - in the sorted order now

        iterator = elements.iterator();

        while (iterator.hasNext()) {

            IXml element = (IXml)iterator.next();

            // add the element back to its parent element

            parent.addChildElement(element);

        }

        System.out.println("!!!!!!Returning from SortInvioceReportLJO.sort== "+result);

        return result;

    }

// Custom Comparator Class

public class CustomComparator implements Comparator {

              public int compare(Object o1, Object o2) {

                     System.out.println("In CustomComparator compare !!  ");

                     IXml e1;

                     IXml e2;

                     SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy");

                     int i = 0;

                     try{

                     if((o1 instanceof IXml) && (o2 instanceof IXml)){

                          

                           e1 = (IXml)o1;

                           e2 = (IXml)o2;

                           System.out.println("In Comparator o1!!! "+o1);

                           System.out.println("In Comparator o2!!! "+o2);

                          

                           i = sdf.parse(e2.getText("Invoice/Date")).compareTo(sdf.parse(e1.getText("Invoice/Date")));

                           if(i==0){

                                  i = (Integer.valueOf((e1.getText("Invoice/InvoiceId")))).compareTo(Integer.valueOf((e2.getText("Invoice/InvoiceId"))));

                           }

                           System.out.println("In Comparator i === "+i);

                    

                     }

              }catch(ParseException ex){

                     System.out.println("CustomComparator Exception in Parsing !!  "+ex);

              }

                    

                     return i;

              }

       }

Hope it'll be helpful.