how to use JSTL Tag in jsp?

Question

I am not used to the JSTL tag library. I learned the basic use of JSTL for loop. But when I start my project I got some complexity. In this stage, I can't figure out how to use JSTL. the JSP page code below.

<%
    //get the group list for post
    GroupOperation gpo = new GroupOperation(DBConnection.getConnection());
    List<Groups> groupList = gpo.getGroups();
    pageContext.setAttribute("myGroup", groupList);

   //get the user post
  PostOperation postOperation = new PostOperation(DBConnection.getConnection());
  List<Posts> postList = postOperation.getAllPost();
  pageContext.setAttribute("psList", postList);
  if (postList == null) {
    System.out.println("there is no post to show");
    }
%>

 <%
         for (GroupMembers memgr : grm) {
              for (Posts p : postList) {
                if (memgr.getGroupId() == p.getGroupId()) {
%>
                 <h4><%= gpo.getSingleGroup(p.getGroupId()).getGroupName()%></h4>
<%
                }
            }
        }
%>

<%= gpo.getSingleGroup(p.getGroupId()).getGroupName()%> this is my most complexity part. i will always be appreciate for your answere.

Answer 1

First you need to add jstl jar file in your build path. and use following code, I hope it will help you and get some idea

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt"%>

<c:forEach items="grm" var="memgr">
    <c:forEach items="postList" var="p">
        <c:if test="${memgr.groupId eq p.groupId}">
              <h4>
                    ${gpo.getSingleGroup(p.getGroupId()).groupName}
              </h4>
        </c:if>
    </c:forEach>
</c:forEach>