Question

I am developing a comment forum that is people will comment and can see their comments after posting but i am getting null pointer exception in servlet.

index.jsp

<form action="Comment" method="post">

  <textarea style="resize: none;" cols="30" rows="3" id="myTextarea" name="myTextarea"></textarea>

</form>

Comment servlet

  try{
    String comment=request.getParameter("myTextarea");

       ArrayList al1=null;
        ArrayList emp_list =new ArrayList();
         al1.add(comment);       
         emp_list.add(al1);                 
         request.setAttribute("empList",emp_list);        
        String nextJSP = "/result.jsp";
       RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(nextJSP);
      dispatcher.forward(request,response);
    }       
    catch(Exception e){       
    out.println("exception"+e);//exception coming 

    }

Answer 1

You al1 will be null when you try to add to it:

ArrayList al1=null;
ArrayList emp_list =new ArrayList();
al1.add(comment); 

Try changing the first line to:

ArrayList al1 = new ArrayList();

This will result in forwarding an array list inside an array list to your next jsp page. It might be simpler to just do:

ArrayList emp_list =new ArrayList();
emp_list.add(comment); 

…and remove the varialble al1 altogether.