Java ArrayList using in JSTL()

Question

i want foreach items add arrays list

<sql:query var="query"  dataSource="${db}">

   select fname, lname from users where fname='ali'

</sql:query>

<c:forEach items="${query.rows}" var="result"> 

 <% 

  ArrayList l= new ArrayList();
  l.add("${result.fname}");
  l.add("${result.lname}");


 for(int i=0; i<l.size(); i++)
   {
   out.println(l.get(i));
   }
 %>

</c:forEach>

output result:

${result.fname} ${result.lname}  ${result.fname} ${result.lname}  ${result.fname} ${result.lname}

what is wrong ?

jsp is meant for presentation purposes only , so try populating the list in servlet and passing it back to the jsp . it would be easy to find the errors — Santhosh, Apr 21 '14 at 10:16
You can't use jstl inside scriptlet.. Please go through JSP lifecycle and tag library... — Shashi, Apr 21 '14 at 10:16
@maxx777 the generated servlet will recognize ${result.fname} as static value.. — Shashi, Apr 21 '14 at 10:21

Shashi · Accepted Answer · 2014-04-21T11:14:01.350

You can't use jstl inside scriptlet..

Save the value of ${result.fname} using <c:set> in page scope. And use the variable inside the scriptlet.

e.g.

<c:forEach items="${query.rows}" var="result">
     <c:set var="lname" value="${result.lname}"  />
     <c:set var="fname" value="${result.fname}" />

     <%
         ArrayList l= new ArrayList();

         l.add((String)pageContext.getAttribute("fname"));
         l.add((String)pageContext.getAttribute("lname"));

         for(int i=0; i<l.size(); i++)
         {
             out.println(l.get(i));
         }
     %>


</c:forEach>

For more information, http://docs.oracle.com/javaee/1.4/tutorial/doc/JSTL4.html

http://javapapers.com/jsp/jsp-life-cycle-explain/

http://docs.oracle.com/cd/E13222_01/wls/docs81/taglib/handler.html

UPDATE

EL attributes are stored in the scope - page, request, session, application The <c:set> tag example doesn't specify a scope, so therefore you could get it like this:

 <c:set var="fname" value="${result.fname}" />

  <%
       String fname = (String)pageContext.getAttribute("fname"); 
       System.out.println(fname);
  %>

alternatively exploit the feature of the useBean tag that creates a scriptlet variable:

<c:set var="fname" value="${result.fname}" />
<jsp:useBean id="fname" type="java.lang.String"/>
<%
  System.out.println(fname);
 %>

Note that the EL variable and the Scriptlet variable are initially pointing at the same String. But changing the string in scriptlet code will change the value it is pointing at, while leaving the EL variable untouched.

thank you @Shashi. now code work correct (sorry my English very bad) — Beginner, Apr 21 '14 at 10:51

score 1 · Answer 2 · edited Apr 21 '14 at 11:06

1

As you are adding ${result.fname} using quotes. JVM considers it as string literals. So you are getting result like this.

edited Apr 21 '14 at 11:06

Aniket Kulkarni

12,825
9
67
90

answered Apr 21 '14 at 10:18

Mayur Bhindi

48
6

score 0 · Answer 3 · edited May 23 '17 at 11:45

0

use foreach loop in jstl for eg check out the eg here!

and avoid java code in jsp page check out this link

How to avoid Java code in JSP files?

edited May 23 '17 at 11:45

Community

1
1

answered Apr 21 '14 at 10:29

Atiq

166
2
6
21

Java ArrayList using in JSTL()

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