gui not updating performing crud operations

[obaid abbassi]

I m using boostrap cards to show notes when I add note it shows on screen but whenever I update it it is updated and deleted from db but changes are not relected in frontend

<div class="contaner d-flex justify-content-center">

  <div class="card" style="width: 30rem;">
    <div class="card-body crb">

      <form action="noteServ" method="post">
        <div class="form-group  fm">


          <label for="exampleInputEmail1">Note Title</label>
          <input type="text"  name="note-title"  class="form-control" id="exampleInputEmail1" aria-describedby="emailHelp" placeholder="enter title">
        </div>
        <div class="form-group fm">
          <label for="exampleInputEmail1">Note Description</label>
          <textarea class="form-control" id="exampleFormControlTextarea1" rows="3" name="note-des" style="resize: none"></textarea>
        </div>

        <button type="submit" class="btn btn-outline-info w-100" style="margin-top:10%;">Add Note</button>
        <a href="index.jsp">Back to home</a>
      </form>



    </div>
  </div>


</div>



<%
    try {
  List<notes> notes = (List<model.notes>) request.getSession().getAttribute("list");


  for (notes n : notes) {





                                              %>



<div class="outer text-center d-flex flex-row ">
  <div class="row mt-5 mb-3 flex-row" style="margin:auto;">

    <div class="col-md-4 col-12">

      <div class="card" style="width: 18rem;" id="card">
        <section class="d-flex justify-content-end icon">
          <a href="edit.jsp?Id= <%=n.getNoteID()%> &Id2= <%=n.getNoteDescription()%>&Id3=<%=n.getNoteName()%> " ><i class="fa-solid fa-pencil"></i></a>
<a href="del.jsp?Id=<%=n.getNoteID()%>"> <i class="fa-solid fa-trash" onclick="trash()"></i></a>



        </section>




        <div class="card-body">
          <h5 class="card-title"><%=n.getNoteName()%></h5>
          <h6 class="card-subtitle mb-2 text-muted"><hr></h6>
          <p class="card-text"><%=n.getNoteDescription()%></p>
          <small style="color:green">Date is :<%=n.getNoteDate()%> </small>
          <small style="color:green">Id is :<%=n.getNoteID()%> </small>
        </div>
      </div>
    </div>




  </div>



</div>

  <%





  }





      }catch (Exception e){} %>

[Campbell Ritchie]

Is that an empty catch (...) in line 95? An empty catch might be causing you to ignore an exception.

[obaid abbassi]

one more thing when I use boostrap cards it perfectly align horizontally but when It comes under the loop whole cards shown vertically why

<%


 for (int i=0;i<6;i++)
 {
     %>

<div class="row">


 <div class="col-md-4">


   <div class="card" style="width: 18rem;">
     <img src="..." class="card-img-top" alt="...">
     <div class="card-body">
       <h5 class="card-title">Card title</h5>
       <p class="card-text">Some quick example text to build on the card title and make up the bulk of the card's content.</p>
       <a href="#" class="btn btn-primary">Go somewhere</a>
     </div>
   </div>





 </div>






</div>


     <%}



%>

[Ron McLeod]

If you would print the exceptions (or let them bubble-up) rather than hiding them, you would probably get some clues as to what it going wrong.

catch (Exception e){}

[obaid abbassi]

java.lang.NullPointerException: Cannot invoke "java.util.List.iterator()" because "notes" is null

I got the exception

[Ron McLeod]

obaid abbassi wrote:java.lang.NullPointerException: Cannot invoke "java.util.List.iterator()" because "notes" is null

Then, I guess request.getSession().getAttribute("list") is returning null.  Check your code where you think you are setting a value for list and make sure that it is not null at that point.

[obaid abbassi]

  try {
 List<notes> notes = (List<model.notes>) request.getSession().getAttribute("list");

out.print(notes);}catch...

I checked it shows items in it

[obaid abbassi]

whenever I login.jsp to notes.jsp first time I got this exception notes are null but in db notes are there

[Ron McLeod]

I don't know if this is part of your problem, but is seems like bad idea to use the same name for a local variable and a class.

List<notes> notes = (List<model.notes>) request.getSession().getAttribute("list");
for (notes n : notes) {

Follow the common Java coding standards and rename  your class to Notes

[obaid abbassi]

<%
   try {
 List<Notes> notes = (List<Notes>) request.getSession().getAttribute("list");

out.print(notes);
 for (Notes n : notes) {






                                             %>



<div class="outer text-center d-flex flex-row ">
 <div class="row mt-5 mb-3 flex-row" style="margin:auto;">

   <div class="col-md-4 col-12">

     <div class="card" style="width: 18rem;" id="card">
       <section class="d-flex justify-content-end icon">
         <a href="edit.jsp?Id= <%=n.getNoteID()%> &Id2= <%=n.getNoteDescription()%>&Id3=<%=n.getNoteName()%> " ><i class="fa-solid fa-pencil"></i></a>
<a href="del.jsp?Id=<%=n.getNoteID()%>"> <i class="fa-solid fa-trash" onclick="trash()"></i></a>



       </section>




       <div class="card-body">
         <h5 class="card-title"><%=n.getNoteName()%></h5>
         <h6 class="card-subtitle mb-2 text-muted"><hr></h6>
         <p class="card-text"><%=n.getNoteDescription()%></p>
         <small style="color:green">Date is :<%=n.getNoteDate()%> </small>
         <small style="color:green">Id is :<%=n.getNoteID()%> </small>
       </div>
     </div>
   </div>




 </div>



</div>

 <%





 }





     }catch (Exception e){

     e.printStackTrace();
 } %>

[obaid abbassi]

    public List<Notes> readingNotes( ) {

        List<Notes> list = new ArrayList<>();
        try {


            userRegistration user = new userRegistration();

            Class.forName("com.mysql.cj.jdbc.Driver");

            Connection conn = DriverManager.getConnection(url, "root", "");

            String sql = " select * from notes";
            PreparedStatement stmt = conn.prepareStatement(sql);


            ResultSet rs = stmt.executeQuery();

            while (rs.next()) {


                String title = rs.getString("noteTitle");
                int ID = rs.getInt("noteID");
                String Des = rs.getString("noteDescription");
                String date = rs.getString("noteDate");
                Notes obj=new Notes();
          obj.setNoteName(title);

          obj.setNoteDescription(Des);
obj.setNoteID(ID);

obj.setNoteDate(date);
          list.add(obj);



            }

conn.close();

        } catch (Exception e) {
            e.printStackTrace();
        }

        return list;

    }

this the code where i m reading my nots

[obaid abbassi]

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Notes notes=new Notes();
        PrintWriter out=response.getWriter();



Dao user=new Dao();

String noteName=request.getParameter("note-title");


        String noteDes=request.getParameter("note-des");


    String nm= notes.setNoteName(noteName);
            String des=notes.setNoteDescription(noteDes);

       boolean chk= user.isNoteInserted(nm,des);
      List<Notes> list= user.readingNotes();




     if(chk){

         HttpSession httpSession= request.getSession();

         httpSession.setAttribute("list",list);
        RequestDispatcher ob =request.getRequestDispatcher("notes.jsp");

        ob.forward(request,response);
     }
     else {

         out.println("something went wrong...");
     }


    }
}

this is the servelt receiving and performing dao