Updating ArrayList with servlets n jsp

Question

Sir i have an issue of updating my array list connected wd jsp n action servlet along wd form bean..

here is my frst jsp page where i m displaying the list:i want to update this list wd servlet where roll no will be the condition do help??

<%Iterator itr;%>
<% ArrayList data= (ArrayList)request.getAttribute("data");
    for (itr=data.iterator(); itr.hasNext(); )
    {


%>
    <tr>

        <td width="40"> <input type="text" value="<%=itr.next()%>"/></td>
        <td width="40"><input type="text"  name="th2" value="<%=itr.next()%>"/></td>
            <td width="40"><input type="text"  value="<%=itr.next()%>"/></td>
    <td width="40"><input type="text"  value="<%=itr.next()%>"/></td>
            <td width="40"><input type="text"  value="<%=itr.next()%>"/></td>
            <td width="40"><input type="text"  value="<%=itr.next()%>"/></td>

</tr>
<%}%>

(1) [Avoid Scriptlets in JSP](http://stackoverflow.com/questions/3177733/how-to-avoid-java-code-in-jsp-files) (2) you are calling `.next()` so many times inside the loop ! (3) Your question is not clear , please elaborate on the flow. — AllTooSir, Jul 24 '13 at 19:24
ok forget dis code just help me wd dis how can i update table which has name and marks along wd roll no? My aim is to update the table keeping rollno as primary key — Kunal Mahajan, Jul 25 '13 at 10:58
Whyere do you want to update ? DB or inside the JSP page itself ? — AllTooSir, Jul 25 '13 at 10:59
Then you need to send the values to the server side , submit a form using `POST` or make an ajax call . — AllTooSir, Jul 25 '13 at 11:02
ok bt hw will i store loop values for eg there will be many names?should i use array for dat? — Kunal Mahajan, Jul 25 '13 at 11:03
Instead of asking me , google it , your requirement is very basic , you will get lots of examples in net , you can type JSON in net and you will get tutorials. — AllTooSir, Jul 25 '13 at 11:06

score 0 · Answer 1 · answered Jul 24 '13 at 19:27

That is not how an iterator works. iter.hasNext specifies whether there are more elements. iter.next advances to the next. You are calling hasNext once, but next 6 times.

You are essentially asking: "Do you have a first element? If so, get me the first 6." But you may only have 2 elements and that will cause an IndexOutOfBoundsException.

The foreach loop syntax automatically fetches an iterator for you so it reduces your code.

Try this:

<% for (Object o : (ArrayList)request.getAttribute("data"))
   {
%>
    <tr>

        <td width="40"> <input type="text" value="<%=o %>"/></td>
        <td width="40"><input type="text"  name="th2" value="<%=o %>"/></td>
        <td width="40"><input type="text"  value="<%=o %>"/></td>
        <td width="40"><input type="text"  value="<%=o %>"/></td>
        <td width="40"><input type="text"  value="<%=o %>"/></td>
        <td width="40"><input type="text"  value="<%=o %>"/></td>

</tr>
<% } %>

Thanks for dis its showing data perfectly bt the main issue is hw can i update the values specified in the table i m not able to understand that — Kunal Mahajan, Jul 25 '13 at 11:00
ok forget dis code just help me wd dis how can i update table which has name and marks along wd roll no? My aim is to update the table keeping rollno as primary key — Kunal Mahajan, Jul 25 '13 at 12:25

Updating ArrayList with servlets n jsp

1 Answers1