How to pass an attribute from JSP to tag file. Override the value in tag, and get the updated value in JSP

Question

I have a JSP where I am declaring an integer value

<c:set var="rowCount" value="0" />

I am trying to use it inside several tags

<product:attribute rowCount="${rowCount}" attrKey="${msg_site}&#58;" attrValue="${product.site}" />
<product:attribute rowCount="${rowCount}" attrKey="${msg_name}&#58;" attrValue="${product.name}" />
<product:attribute rowCount="${rowCount}" attrKey="${msg_type}&#58;" attrValue="${product.type}" />

Inside each tag I am overriding the rowCount value

<%@ attribute name="rowCount"  required="true" %>
<c:if test="${rowCount >= 2}" >
    </div>
    <div class="col-md-12 col-sm-12 col-xs-12 ">
    <c:set var="rowCount" value="${0}" />
</c:if>

<c:set var="rowCount" value="${rowCount +1}" />

But it seems I am declaring a new variable for rowCount in each tag. How do I reuse the value instead of declaring a new variable?

Answer 1

I was trying with adding the scope for only the first declaration of the variable and it was not working.

Then I tried to add for them all, like this:

<c:set var="rowCount" value="0" scope="request" />

and

<%@ attribute name="rowCount"  required="true" %>
<c:if test="${rowCount ge 2}" >
    </div>
    <div class="col-md-12 col-sm-12 col-xs-12 ">
    <c:set var="rowCount" value="${0}" scope="request" />
</c:if>

<c:set var="rowCount" value="${rowCount +1}" scope="request"/>

It worked partially. I was able to add new values to the row count, but the line

    <c:set var="rowCount" value="${0}" scope="request" />

Was not working. It never went back to zero. So I change it to have a local variable and override the value only once. like this:

<%@ attribute name="rowCount"  required="true" %>

<c:set var="rowCountInstance" value="${rowCount}" />

<c:if test="${rowCountInstance ge 2}" >
    </div>
    <div class="col-md-12 col-sm-12 col-xs-12 ">
    <c:set var="rowCountInstance" value="${0}" />
</c:if>

<c:set var="rowCount" value="${rowCountInstance +1}" scope="request"/>

Now I have the result that I want. But I still could not understand why I could not override it twice.