Iterate over a collection and put results in a Variable? - jstl

Question

I tried asking this question but may have worded it wrong. Im doing this:
<c:forEach var="cell" items="${row}" varStatus="rowStatus">
<td class="data_extract">
<c:choose>
<c:when test="${results.types[rowStatus.index].array}">
<c:forEach var="elem" items="${cell}" varStatus="cellStatus">
${elem}<c:if test="${!cellStatus.last}">, </c:if>
</c:forEach>
</c:when>
<c:otherwise>
${cell}
</c:otherwise>
</c:choose>
</td>
For example ${elem} will loop a couple times and will have this in the cell: "10GT, 137S" after the loop is done. I want to maybe concatenante a variable so "10GT, 137S" is assigned a variable so that I might pass into:
<span class="mouseover_text" title="${NEW VARIABLE HERE!!!!!!!}"></span>
Please help a brother...
EDIT:
This seems to work!!
<td class="data_extract">
<c:choose>
<c:when test="${results.types[rowStatus.index].array}">
<c:set var="comma" value="," />
<c:forEach var="elem" items="${cell}" varStatus="cellStatus">
<c:set var="myVar" value="${cellStatus.first ? '' : myVar} ${elem} ${cellStatus.last ? '' : comma}" />
</c:forEach>
<span class="mouseover_text" title="${myVar}">${myVar}</span>
</c:when>
<c:otherwise>
${cell}
</c:otherwise>
</c:choose>
</td>

Answer 1

<td class="data_extract">
<c:choose>
<c:when test="${results.types[rowStatus.index].array}">
<c:set var="comma" value="," />
<c:forEach var="elem" items="${cell}" varStatus="cellStatus">
<c:set var="myVar" value="${cellStatus.first ? '' : myVar} ${elem} ${cellStatus.last ? '' : comma}" />
</c:forEach>
<span class="mouseover_text" title="${myVar}">${myVar}</span>
</c:when>
<c:otherwise>
${cell}
</c:otherwise>
</c:choose>
</td>