From Documentation

Jump to: navigation, search





EL expressions provide the following operators[1]:

Type Operators Description
Arithmetic +, -[2], *, /, div, %, mod, -[3]
  • / and div are the same, while % and mod are the same.
Logical and, &&, or, ||, not, !, empty
  • The empty operator is a prefix operation that can be used to determine whether a value is null or empty, such as ${empty foo}.
Relational ==, eq, !=, ne, <, lt, >, gt, <=, ge, >=, le
  • Comparisons can be made against other values, or against boolean, string, integer, or floating point literals.
Conditional A ? B : C It evaluate B or C, depending on the result of the evaluation of A.
Index []

To evaluate expr-a[expr-b], evaluate expr-a into value-a and evaluate expr-b into value-b. If either value-a or value-b is null, return null.

  • If value-a is a Map, return value-a.get(value-b). If !value-a.containsKey(value-b), then return null.
  • If value-a is a List or array, coerce value-b to int and return value-a.get(value-b) or Array.get(value-a, value-b), as appropriate. If the coercion couldn't be performed, an error is returned. If the get call returns an IndexOutOfBoundsException, null is returned. If the get call returns another exception, an error is returned.
  • If value-a is a JavaBeans object, coerce value-b to String. If value-b is a readable property of value-a, then return the result of a get call. If the get method throws an exception, an error is returned.
Member .
  • Properties of variables are accessed using the . operator and can be nested arbitrarily.
  • The value of a map can be accessed by using the . operator.

  1. The information is from JSP Tutorial.
  2. binary
  3. unary

The relative precedence levels of operators from the highest to lowest, left to right are as follows:

  • [] .
  • ()[1]
  • - [2] not ! empty
  • * / div % mod
  • + - [3]
  • < > <= >= lt gt le ge
  • == != eq ne
  • && and
  • || or
  •  ? :

  1. Used to change the precedence of operators.
  2. unary
  3. binary

Version History

Last Update : 2011/8/3


Version Date Content
     




Copyright © Potix Corporation. This article is licensed under GNU Free Documentation License.