<jsp:useBean id="test" class="java.lang.String" scope="request"/>

<%
         test = "false";
%>

1. outside scriptlet: <c:out value="${test}"/>   <!-- will not print anything -->

<%
    out.println("2. in scriptlet: " + test);     // will print false
%>

<c:set var="test" value="true" />

3. outside scriptlet: <c:out value="${test}"/>   <!-- will print true -->

<%
    out.println("4. in scriptlet: " + test);     // will print false
%>