jspjstlelscriptlet

Accessing a JSTL / EL variable inside a Scriptlet

The following code causes an error:

<c:set var="test" value="test1"/>
<%
    String resp = "abc"; 
    resp = resp + ${test};  //in this line I got an  Exception.
    out.println(resp);
%>

Why can't I use the expression language "${test}" in the scriptlet?

Solution

  • JSTL variables are actually attributes, and by default are scoped at the page context level.
    As a result, if you need to access a JSTL variable value in a scriptlet, you can do so by calling the getAttribute() method on the appropriately scoped object (usually pageContext and request). 

    resp = resp + (String)pageContext.getAttribute("test");

    Full code 

     <c:set var="test" value="test1"/>
 <%
    String resp = "abc"; 
    resp = resp + (String)pageContext.getAttribute("test");   //No exception.
    out.println(resp);
  %>

    But why that exception come to me.

    A JSP scriptlet is used to contain any code fragment that is valid for the scripting language used in a page. The syntax for a scriptlet is as follows:

    <%
   scripting-language-statements
%>

    When the scripting language is set to Java, a scriptlet is transformed into a Java programming language statement fragment and is inserted into the service method of the JSP page’s servlet.

    In scriptlets you can write Java code and ${test} in not Java code.

    Not related