jstl-el problem

[vijay shanker]

Hi friends,

I want to test on the size of a list;

the folllowing didn't work:

  <c:when test="${listName.size!=0}">  

i get error mentioning

javax.servlet.jsp.el.ELException: The "." operator was supplied with an index value of type "java.lang.String" to be applied to a List or array, but that value cannot be converted to an integer.

Any idea on how this can be done?

[Nishan Patel]

Hi,

What is your listName type .??

[vijay shanker]

  		ArrayList<Name> listName = new ArrayList<Name>(0);

this listName is a arraylist

[Sagar Rohankar]

vijay shanker wrote:

  <c:when test="${listName.size!=0}">  

Unfortunately, you can't do this using EL, the right part after DOT is either bean property or hash map key.
Use JSTL <fn:length()>.

[vijay shanker]

Hi there,

then what should be solution if i need to get such functionality

[Stefan Evans]

Two possible solutions
- the empty keyword
- the fn:length function (not available in JSTL1.0)

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

<c:if test="${empty listName}">  You have an empty list </c:if>
<c:if test="${fn:length(listName) == 0}">You have a list of size zero.  Only works in JSTL1.1 or later</c:if>

[Balu Sadhasivam]

Vijay,

Use <c:when test="${empty listName}" > to check the size is 0.

If you want to check for other values (size > 0 ) , put this ArrayList in a bean and in bean define size property and set size property to ArrayList.size and use it as EL in JSP.

[Balu Sadhasivam]

Stefan beat me !!

[Shailesh Narkhede]

you can use [] operator instead of . operator
Using this you can use ArrayList and Arrays in EL.

[Balu Sadhasivam]

you can use [] operator instead of . operator

how would that helps the current problem?

[Sagar Rohankar]

Balu Sadhasivam wrote:

you can use [] operator instead of . operator

how would that helps the current problem?

May be he wants to suggest something like this,

List is empty ${list[0] == null}

Bust this shouldn't be the approach

[Shailesh Narkhede]

Actually I am thinking he want want value from ArrayList,
But he want size of arrayList, I thing we can not get size of arraylist in EL.
Of course we can do Like,
List is empty ${list[0] == null}
but as Sagar says, that is not correct approach because arrayList can contain null 0th element.