Java Platform, Enterprise Edition (Java EE) 8 The Java EE Tutorial

## Overview of the EL

The EL allows page authors to use simple expressions to dynamically access data from JavaBeans components. For example, the `test` attribute of the following conditional tag is supplied with an EL expression that compares 0 with the number of items in the session-scoped bean named `cart`.

    <c:if test="${sessionScope.cart.numberOfItems > 0}">
      ...
    </c:if>

See Using the EL to Reference Managed Beans for more information on how to use the EL in JavaServer Faces applications.

To summarize, the EL provides a way to use simple expressions to perform the following tasks:

- Dynamically read application data stored in JavaBeans components, various data structures, and implicit objects

- Dynamically write data, such as user input into forms, to JavaBeans components

- Invoke arbitrary static and public methods

- Dynamically perform arithmetic, boolean, and string operations

- Dynamically construct collection objects and perform operations on collections

In a JavaServer Faces page, an EL expression can be used either in static text or in the attribute of a custom tag or standard action.

Finally, the EL provides a pluggable API for resolving expressions so that custom resolvers that can handle expressions not already supported by the EL can be implemented.

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