jsp - Accessing a JSTL / EL variable inside a Scriptlet

Question

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?

Answer 1

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.

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