Literal Data and Named Variables

This section describes literal data and named variables used in EL expressions. 5 types of literal data are supported: Boolean, Integer, Floating Point Number, String, and Null.

As in all computer language, expression starts with literal data and variables. EL expression language supports 5 types of literal data:

The literal data rules are easy to understand, with a couple of exceptions:

Named variables are coming from two sources:

Variables provided as pageContext attributes will have their original Java types, like int, float, char, or Object. But all EL operations will be carried out in one of the 5 types of literal data. Operators of other types will be converted before the operation.

Type conversion rules:

Last update: 2012.

Table of Contents

 About This Book

 JSP (JavaServer Pages) Overview

 Tomcat 7 Installation on Windows Systems

 JSP Scripting Elements

 Java Servlet Introduction

 JSP Implicit Objects

 Syntax of JSP Pages and JSP Documents

 JSP Application Session

 Managing Cookies in JSP Pages

 JavaBean Objects and "useBean" Action Elements

 Managing HTTP Response Header Lines

 Non-ASCII Characters Support in JSP Pages

 Performance of JSP Pages

EL (Expression Language)

 What is EL (Expression Language)?

 EL Expression Types and Usage

Literal Data and Named Variables

 Basic Operators and Operations

 Predefined Implicit Objects

 Collection Elements and Object Properties

 Expression Examples in Static Text

 Expression Examples in Static Text - Result

 EL Variables Are pageContext Attributes

 Overview of JSTL (JSP Standard Tag Libraries)

 JSTL Core Library

 JSP Custom Tags

 JSP Java Tag Interface

 Custom Tag Attributes

 Multiple Tags Working Together

 File Upload Test Application

 Outdated Tutorials


 PDF Printing Version