renaming a field and not able to set value to the saved PDF document ...

[Venkatesh Prasad]

I renamed fields in a PDF document "source.PDF" and saved the document as 
'target.PDF". I was then not able to set values to the fields in the saved 
document 'target.PDF". I also observed reduction in the size of the saved PDF - 
source.PDF (3.34 MB) - target.PDF (911 KB).
 
Can anyone help? The code I used to rename the fields is given below:
 
     PDDocument pdfDocument = PDDocument.load(pdfSource);
     try
     {
      if (pdfDocument.isEncrypted())
      {
       pdfDocument.decrypt("");
      }
      PDDocumentCatalog docCatalog = pdfDocument.getDocumentCatalog();
      PDAcroForm acroForm = docCatalog.getAcroForm();
      if (acroForm != null)
      {
       List pdfFields = acroForm.getFields();
       if (pdfFields != null)
       {
        PDField pdfField;
        for (int i = 0; i < pdfFields.size(); i++)
        {
         pdfField = (PDField) pdfFields.get(i);
         String fieldName = pdfField.getPartialName();
         if( fieldName.equalsIgnoreCase("Test1") ){
          String newFieldName = "acco...@name1";
          pdfField.setPartialName(newFieldName);
         }
        }
        pdfDocument.save(pdfOutput);
       } else {
        return "No Acro Form Fields found in PDF Document " + pdfSource + "!";
       }
      } else {
       return "PDF document " + pdfSource + " not able to access!";
      }
     } catch (Exception e) {
      return "PDF Document " + pdfSource + " is encrypted! Cannot process.";
     }
     pdfDocument.close();
 
Thanks & Regards
 
Venkatesh Prasad.B.K.