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Java Forum / General / January 2006JSTL problem
i have put an arraylist in session in my servlet class. session.setAttribute("list",L); i want to use this arrayList in my JSP page to display the list items. i want to use JSTL c:forEach for this purpose. How do i get the arrayList in JSP page ? List RetrievedList =(java.util.List)session.getAttribute("list"); should use this code in my JSP before using the c:forEach tag. otherwise how does my c:forEach gets the list from the servlet ? anybody know JSTL here ? > i have put an arraylist in session in my servlet class. > [quoted text clipped - 10 lines] > should use this code in my JSP before using the c:forEach tag. > otherwise how does my c:forEach gets the list from the servlet ? > anybody know JSTL here ? > [quoted text clipped - 12 lines] >>should use this code in my JSP before using the c:forEach tag. >>otherwise how does my c:forEach gets the list from the servlet ? Just enough to be dangerous. I think that want you want to do is enable the JSP expression language which will allow you to use constructs like (untried and untested) <c:forEach var="x" items="${sessionScope.list}"> If you need more information, I suggest looking at the J2EE tutorial on http://java.sun.com. HTH, Ray  SignatureXML is the programmer's duct tape. > Just enough to be dangerous. I think that want you want to do is enable > the JSP expression language which will allow you to use constructs like > (untried and untested) > > <c:forEach var="x" items="${sessionScope.list}"> OK. so, you meant , in the Action class, should use session.setAttribute("list") And in the JSP, i would pick up this way "<c:forEach var="x" items="${sessionScope.list}">" i see, you are using the "sessionScope" keyword. BUT look at this examle here http://www-128.ibm.com/developerworks/java/library/j-jstl0318/ the code is : <table> <c:forEach items="${entryList}" var="blogEntry"> <tr><td align="left" class="blogTitle"> <c:out value="${blogEntry.title}" escapeXml="false"/> </td></tr> <tr><td align="left" class="blogText"> <c:out value="${blogEntry.text}" escapeXml="false"/> </td></tr> </c:forEach> </table> did you see, they are not using "sessionScope" as you given in your example !!! How they are accessing the list then ....is this code wrong ? >>Just enough to be dangerous. I think that want you want to do is enable >>the JSP expression language which will allow you to use constructs like [quoted text clipped - 30 lines] > example !!! How they are accessing the list then ....is this code > wrong ? No; I only brought up the session scope because you used it in your OP. There is a sequence of scopes that the expression language (EL) will search through to find variable values. Unless you have an explicit need for another scope, I think that the request attribute will fill your needs. If you are serious about using JSTL you should try to obtain a resource that will help you understand it. Don't expect to simply jump right in and have everything be easy. The J2EE tutorial on http://java.sun.com has many examples. HTH, Ray SignatureThis signature intentionally left blank. >No; I only brought up the session scope because you used it in your OP OK...thats correct. but How those guys (the code i posted from IBM tutorial) are doing it then ? How they are accessing the list ? they are using this... <c:forEach items="${entryList}" var="blogEntry"> did you see, they are NOT using session scope,page scope,application scope ..nothing !......how they are picking up the data in the JSP ? How is this entryList picked up ? >There is a sequence of scopes that the expression language (EL) will >search through to find variable values. Unless you have an explicit >need for another scope, I think that the request attribute will fill >your needs. suppose, i have put the list in the session scope in the Action class. Now, how the JSTL would find it ? Now, if i have <c:forEach items="${entryList}" var="blogEntry"> scan 1: the JSTL first scan request scope whether the lis is there or not....if it fails scan 2: the JSTL would scan session scope whether the lis is there or not....if it fails scan 3: the JSTL would scan page scope whether the lis is there or not.....if it fails scan 4: the JSTL would scan application scope whether the lis is there or not..... IF all of them fails, then NULL pointer exception. is this approach JSTL follows while searching a list when no scope is specified in the JSP. thank you >>No; I only brought up the session scope because you used it in your OP > [quoted text clipped - 40 lines] > is this approach JSTL follows while searching a list when no scope is > specified in the JSP. It is something like that. I can't confirm a couple of things above, but you have the general idea. Either dig through the specs or write some examples to flesh out the other parts. I don't know what the specific order is for searching the scopes. I would imagine that page scope comes before session scope however. I also can't confirm what the behavior is when the data is not found. I would hope for a regular subclass of Exception, not NullPointerException, which extends RuntimeException. HTH, Ray SignatureThis signature intentionally left blank. There are plenty of examples of how to use the forEach tag in this tutorial. http://www-128.ibm.com/developerworks/java/library/j-jstl0318/ Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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