ireport with struts2

[sathya rajavel]

Here Arraylist contains value but the datasource returns null.please please help me

   public String printPDF()  {
                              log.info("===========PDF Printing===============");  
                              
                             
                              
                            
                              ArrayList<OperRepDTO> printpdf=new ArrayList<OperRepDTO>();
                               log.info(operRepList.size());  
                               printpdf.addAll(operRepList);
                                log.info(printpdf.size());  
                             
                              return SUCCESS;

 <action name="printOperReport" class="OperRepAction" method="printPDF">                 
                    <result name="success" type="jasper">            
                        <param name="location">/WEB-INF/CFS .jasper</param>         
                        <param name="dataSource">printpdf</param>        
                        <param name="format">PDF</param>  
                       
                 </result>  
                 </action>