I have a 2d array stored in a java bean and I'm trying to iterate through its contents to print a corresponding table on a JSP page. The array is a bean data member which I'm accessing through the EL code ${board.cells}. I tried to do this with a c:forEach tag, but it's only printing a single cell. I know the array contents are valid, as I can see them when I index them directly by ${board.cells[0][0]}
Here's my loop code, embedded in the JSP.
<c:forEach items="${board.cells}" var="row">
<tr>
<c:forEach items="${row}" var="cell">
<td><img src=${cell} align="" alt="cell"></td>
</c:forEach>
</tr>
</c:forEach>
Any help is much appreciated!
As per the comments, JSTL core tags are simply not been interpreted/parsed. They are been sent plain to the HTML response. You need to declare the JSTL core taglib in top of your JSP to get them to run.
<%# taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
See also:
Our JSTL wiki page
Related
I'm working on a legacy Tomcat server that is no longer supported by the software developer that provided it. web.xml doesn't tell me what version of JSP I'm working with, but all the .class files are Java 1.5.
I have a customer who is upset, because the system has html boxes that are auto-populated by Java, and it fills it straight the the (unordered) results of an XML database query. I'm trying to sneak a bit of code into the JSP for the Selector to sort the list of fields before they are populated, but it doesn't work and I don't understand why.
The (abridged) relevant code:
<%# page import="src.explorer.ObjectStateFactory"%>
<%# page language="java" %>
<%# taglib uri="/WEB-INF/c.tld" prefix="c" %>
<jsp:useBean id="ExplorerViewContext" scope="session" type="src.explorer.ExplorerViewContext"/>
...
<c:forEach var="nc" items="${ExplorerViewContext.networkControllers}">
<c:choose>
<c:when test="${nc.name == ExplorerViewContext.networkControllerSelection.name}">
<option value="<c:out value="${selectAction}${nc.objectKey}"/>" selected><c:out value="${nc.name}"/></option>
</c:when>
<c:otherwise>
<option value="<c:out value="${selectAction}${nc.objectKey}"/>"><c:out value="${nc.name}"/></option>
</c:otherwise>
</c:choose>
</c:forEach>
</select>
The relevant code with my additions:
<%# page import="src.explorer.ObjectStateFactory"%>
<%# page import="java.util.*"%>
<%# page language="java" %>
<%# taglib uri="/WEB-INF/c.tld" prefix="c" %>
<jsp:useBean id="ExplorerViewContext" scope="session" type="src.explorer.ExplorerViewContext"/>
...
<%
final Comparator<src.explorer.XmldbObjectState> NC_ORDER = new Comparator<src.explorer.XmldbObjectState>(){
public int compare(src.explorer.XmldbObjectState nc1, src.explorer.XmldbObjectState nc2){
return nc1.getName().compareTo(nc2.getName());
}
};
List myList = ExplorerViewContext.getNetworkControllers();
java.util.Collections.sort(myList,NC_ORDER);
%>
<c:forEach var="nc" items="${myList}">
<c:choose>
<c:when test="${nc.name == ExplorerViewContext.networkControllerSelection.name}">
<option value="<c:out value="${selectAction}${nc.objectKey}"/>" selected><c:out value="${nc.name}"/></option>
</c:when>
<c:otherwise>
<option value="<c:out value="${selectAction}${nc.objectKey}"/>"><c:out value="${nc.name}"/></option>
</c:otherwise>
</c:choose>
</c:forEach>
</select>
Basically, I'm trying to grab the list and sort it before it gets sent to the HTML. The problem is, myList always comes up empty, and I don't understand why. I'm guessing that ExplorerViewContext.networkControllers in the original code is calling the getNetwrokControllers() method on an instance of ExplorerViewContext, yes? Why can't I do the same thing in a scriptlet and reformat the output a little before serving it?
You should not add scriptlet code to code that is already using JSTL only. The better thing to do would be to edit the bean class src.explorer.ExplorerViewContext to sort the insides for you automatically.
In any case, the reason ${myList} does nothing in the JSTL is that variables created in scriptlets (i.e. between <% and %>) do not exist for JSTL. To get a variable to exist in JSTL you have to create it in JSTL, or set it in the page context, or it has to be in the session or the request. Generally you put it in the session or request in a servlet.
In this case, your list is in the bean, so it would be better to just edit the bean class to sort the list. But you could set the variable into the page context here so that JSTL can use it:
<%
...
List myList = ExplorerViewContext.getNetworkControllers();
java.util.Collections.sort(myList,NC_ORDER);
pageContext.setAttribute("myList", myList); //set in pageContext so JSTL can see it
%>
<c:forEach var="nc" items="${myList}">
As far as the code being "legacy" adding scriptlets to it would make it even more legacy. The fact is, this code is more modern than the modifications you were trying to add. But only slightly so, since using <jsp:useBean> is an obsolete way of using beans.
Hi I am trying to print the list of strings stored in ArrayList object using JSTL, here is my jsp page:
<%#page import="java.util.ArrayList"%>
<%#page import="java.util.List"%>
<%# taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%
List<String> al = new ArrayList<String>();
al.add("testing1");
al.add("testing2");
al.add("testing3");
al.add("testing4");
al.add("testing5");
System.out.println("hello"+ al);
%>
<c:forEach var="alla" items="${al}" >
<c:out value="Hello text"></c:out>
<c:out value="${alla}"></c:out>
</c:forEach>
when i see output it is not showing any thing on the browser, I have printed it using foreach it is showing the result where as in JSTL it is not printing ?
jstl is used to print the objects from the session or request scopes. you did not set your List al either of those .
Try adding it to the session and then access it through jstl
HttpSession session = request.getSession();
session.setAttribute("al", al);
and use c:forEach to print it in your page.
See also
Scope of jsp objects
How do i use jstl
Add values to arraylist use JSTL
how do i create an arraylist inside jsp using jstl
I have simple jsp page (page.jsp), and a simple java class (classWithArray) with an arraylist (list) in it.
How can I get access to the arraylist from jsp, for example to show it in a table?
Use JSTL's forEach tag to iterate over a collection (an ArrayList in this case in particular) inside a JSP, take a look at this post for more details.
you can iterate over an ArrayList using c:forEach tag from JSTL
Below is the sample code which iterates over an peopleList List.
<c:forEach var="person" items="${people.peopleList}">
<tr>
<td>${person.name}</td>
</tr>
</c:forEach>
use page tag to import a java.util.List in your JSP page use
<%# page import="java.util.List" %>
Is there a standard way of printing an array/collection elements of javabeans in JSP? All I know is the <jsp:getProperty> tag which can't do this. I know it can be done using custom tags, but it being such an essential requirement should be provided by JSP.
Also, I have read that using setAttribute() method of PageContext, ServletContext etc we can in a Servlet get the bean and work on it, but it's giving me null value.
pageContext.getAttribute("beanPropertyVariable") //set in page scope
application.getAttribute("beanPropertyVariable") //set in application scope
How can I achieve this?
The standard way is using JSTL <c:forEach>.
Assuming that ${beans} represents the collection of javabeans, here's an example:
<%# taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
...
<c:forEach items="${beans}" var="bean">
${bean.property1}<br/>
${bean.property2}<br/>
${bean.property3}<br/>
</c:forEach>
That's also the simplest way you can get.
See also:
Our JSTL wiki page
Our Javabeans wiki page
you can use JSTL c:foreach tag like below
<c:forEach items="${list}" var="var">
${var}<br/>
</c:forEach>
I am trying (and learning) to build a java web framework, and in the process of developing its' code generator based on the content of the database. In the view making process, I stumble in a difficulty, which I don't know how to solve it.
Firstly, I want all the pages to be created using the following index.jsp :
<body>
<%# include file="header.jsp" %>
<hr/>
<%# include file="body.jsp" %>
<hr/>
<%# include file="footer.jsp" %>
</body>
And, in the body.jsp, I want it to be like this :
<jsp:include page="${application_modul}" %>
Where application_modul is an attribute defined in its' controller this way :
request.setAttribute("application_modul","user_account\\view_user_account.jsp");
It can find the file correctly, but the processed jsp is not what I expected. Here :
<c:forEach items="[application.models.UserAccountModel#18a49e0, application.models.UserAccountModel#1f82982]" var="item" varStatus="status" >
<tr>
....
You can see the items attribute of jstl forEach, got its variable name (toString())...
Any Idea what the problem is????
I hope I describe my problem correctly
Many thanks!
PS :
I already create a quick fix for this, but not what I want it though. In the generated view_user_account.jsp, I do it like this :
<body>
<%# include file="header.jsp" %>
<hr/>
<c:forEach items="${row}" var="item" varStatus="status" >
<tr>
....
<hr/>
<%# include file="footer.jsp" %>
</body>
You can see that I create the whole file here...
EDITED:
PS : ${row} is an ArrayList populated with data from certain table
So, to summarize your problem in a single sentence, JSTL tags are not been parsed and they end up plain in generated HTML output?
You need to declare JSTL taglib in top of the JSP page where you're using JSTL tags to get them to run. For the JSTL core taglib, that'll be
<%#taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
I am not sure but, Try this...
index.jsp
<jsp:param name="parameterName" value="{parameterValue | <%= expression %>}" />