JSTL Modify a collection
<%@ taglib uri="http://java.sun.com/jstl/core" prefix="c" %> <c:if test="${pageContext.request.method=='POST'}"> <c:choose> <c:when test="${param.add!=null}"> <c:if test="${list!=null}"> <c:set var="list" value="${list}," scope="session" /> </c:if> <c:set var="list" value="${list}${param.item}" scope="session" /> </c:when> <c:when test="${param.remove!=null}"> <c:set var="list2" value="" /> <c:forEach var="item" items="${list}"> <c:if test="${item!=param.item}"> <c:if test="${list2!=''}"> <c:set var="list2" value="${list2}," /> </c:if> <c:set var="list2" value="${list2}${item}" /> </c:if> </c:forEach> <c:set var="list" value="${list2}" scope="session" /> <c:remove var="list2" /> </c:when> </c:choose> </c:if> <html> <head> <title>Updatable Collections</title> </head> <body> <table border="0"> <form method="post"> <tr bgcolor="blue"> <td colspan="2"> <font color="white">Updatable Collections</font> </td> </tr> <tr> <td valign="top"> <select NAME="choice" SIZE="5" width="20"> <c:forEach var="item" items="${list}"> <option> <c:out value="${item}" /> </option> </c:forEach> </select> </td> <td valign="top">Enter a item to add or remove. <br /> <input width="20" maxwidth="20" name="item" size="20" /> <br /> <input type="submit" name="add" value="Add" /> <input type="submit" name="remove" value="Remove" /> </td> </tr> </form> </table> </body> </html>