Module Null pointer exception

Question

Hi,
I am having a problem with my module written for Enhancing functionality of file adapter.My module validates a input file for a particular record presence and if that record is present it would be processed normally by XI system.
But in case, if the input file doesn't contain the particular record the module is supposed to throw an exception and process shuld terminate.In this case XI shuldn't process the input file.
But in second case(File not containing the record) I am getting Null pointer exception in adapter monitor.Unable to see any message in auditlog since input file is not being read by file adapter.
My code is like this:
public ModuleData process(ModuleContext moduleContext, ModuleData inputModuleData)
          throws ModuleException {
          // TODO Auto-generated method stub
          //Declarations
          Message mes = null;
          XMLPayload xmlData = null;
          DocumentBuilderFactory docBuilderFactory = null;
          DocumentBuilder docBuilder = null;
          Document doc = null;
          AuditMessageKey amk = null;
          boolean flag = false;
          // Fetch the Message Data from Module Data
          mes = (Message) inputModuleData.getPrincipalData();
          // For Audit Log Fetch the Audit Message key from the message.
          amk = new AuditMessageKey(mes.getMessageId(), AuditDirection.OUTBOUND);
          Audit.addAuditLogEntry(amk,     AuditLogStatus.SUCCESS, "Amex Validation Module called");
          xmlData = mes.getDocument();
          InputStream instr = xmlData.getInputStream();
          docBuilderFactory = DocumentBuilderFactory.newInstance();
          try {
               docBuilder = docBuilderFactory.newDocumentBuilder();
          } catch (ParserConfigurationException e) {
               // TODO Auto-generated catch block
               Audit.addAuditLogEntry(amk,     AuditLogStatus.ERROR, "Document Builder Factory not generated Properly");
          try {
               doc = docBuilder.parse(instr);
          } catch (SAXException e1) {
               // TODO Auto-generated catch block
               Audit.addAuditLogEntry(amk,     AuditLogStatus.ERROR, "Document Not generated Properly, SAX Exception called, May Data contains Error");
          } catch (IOException e1) {
               // TODO Auto-generated catch block
               Audit.addAuditLogEntry(amk,     AuditLogStatus.ERROR, "Document Not generated Properly, Input/Output Error");
          NodeList record = doc.getElementsByTagName("Recordset");
          for (int k = 0; k < record.getLength(); k++) {
               Node recordnode = record.item(k);
               NodeList list_rec = recordnode.getChildNodes();
               for (int l = 0; l < list_rec.getLength(); l++) {
                    String headnodename =
                         list_rec.item(l).getNodeName().toString();
                    if (headnodename.equals("itemType9"))  {
                           flag = true;
          if (flag == true)
               Audit.addAuditLogEntry(amk,     AuditLogStatus.SUCCESS, "Record Type 9 present in the file, Successfully Processed");
          else{
               Audit.addAuditLogEntry(amk,     AuditLogStatus.ERROR, "Record Type 9 not present in the file, Not process further");
               //throw exception
               ModuleException e = new ModuleException();
               throw(e);               
          return inputModuleData;

Answer 1

Are you sure the following statement is going to work always ?
NodeList record = doc.getElementsByTagName("Recordset");
In case there are no nodes by the name <b>Recordset</b>, the very next block of code will throw a NullPointerException at the line
for (int k = 0; k < record.getLength(); k++) {
because, if record is null, record.getLength() would not work and throw NLP.