Java

Implicit objects

See a complete list here: expression language implicit objects

• initParam [1]: The JSP Expression Language (EL) defines implicit objects, which initParam is an example of. When working in JSP pages, you can utilize implicit objects using dot notation and placing expressions within EL delimiters (${...}). For example, if you have an initialization parameter named myParam (defined in web.xml), you can access it from a JSP page with the expression:
  ${initParam.myParam}.
• pageContext [1]: is another implicit object defined by the JSP Expression Language. Ex.: The EL expression uses the PageContext to access the current request (an HttpServletRequest object). From HttpServletRequest, thegetQueryString() method is called to obtain the value of the request's query string:
  <c:when test="${category.id == pageContext.request.queryString}">

Resources

[1] - The NetBeans E-commerce Tutorial - Connecting the Application to the Database