Overview

This reference is split up into the following sections:

  1. Language Elements
  2. Literals
  3. Functions
  4. Operators

For more technical information about the JEXL Grammar, you can find the JavaCC grammar for JEXL here: Parser.jj

Language Elements

ItemDescription
Comments Specified using ## and extend to the end of line, e.g. 
## This is a comment
Identifiers / variables Must start with a-z, A-Z, _ or $. Can then be followed by 0-9, a-z, A-Z, _ or $. e.g.
  • Valid: var1,_a99,$1
  • Invalid: 9v,!a99,1$

JEXL also supports ant-style variables, e.g. 

my.dotted.var
is a valid variable name.

NOTE: JEXL does not support variables with hyphens in them, e.g. 

commons-logging
is not a valid variable, but instead is treated as a subtraction of the variable logging from the variable commons

Scripts A script in Jexl is made up of zero or more statements.
Statements A statement can be the empty statement, the semicolon (;) , block, assignment or an expression. Statements are optionally terminated with a semicolon.
Block A block is simply multiple statements inside curly braces ({, }).

Literals

ItemDescription
Integer Literals1 or more digits from 0 to 9
Floating point Literals 1 or more digits from 0 to 9, followed by a decimal point and then one or more digits from 0 to 9.
String literals Can start and end with either ' or ", e.g. 
"Hello world"
and 
'Hello world'
are equivalent.
Boolean literals The literals true and false can be used, e.g. 
val1 == true
Null literal The null value is represented as in java using the literal null, e.g. 
val1 == null

Functions

FunctionDescription
empty Returns true if the expression following is either:
  1. null
  2. An empty string
  3. An array of length zero
  4. A collection of size zero
  5. An empty map
empty(var1)
size Returns the information about the expression:
  1. Length of an array
  2. Size of a List
  3. Size of a Map
  4. Size of a Set
  5. Length of a string
size("Hello")
returns 5.

Operators

OperatorDescription
Boolean and The usual && operator can be used as well as the word and, e.g. 
cond1 and cond2
and 
cond1 && cond2
are equivalent
Boolean or The usual || operator can be used as well as the word or, e.g. 
cond1 or cond2
and 
cond1 || cond2
are equivalent
Boolean not The usual ! operator can be used as well as the word not, e.g. 
!cond1
and 
not cond1
are equivalent
Equality The usual == operator can be used as well as the abbreviation eq. For example 
val1 == val2
and 
val1 eq val2
are equivalent.
  1. null is only ever equal to null, that is if you compare null to any non-null value, the result is false.
  2. Equality uses the java equals method
Inequality The usual != operator can be used as well as the abbreviation ne. For example 
val1 != val2
and 
val1 ne val2
are equivalent.
Less Than The usual < operator can be used as well as the abbreviation lt. For example 
val1 < val2
and 
val1 lt val2
are equivalent.
Less Than Or Equal To The usual <= operator can be used as well as the abbreviation le. For example 
val1 <= val2
and 
val1 le val2
are equivalent.
Greater Than The usual > operator can be used as well as the abbreviation gt. For example 
val1 > val2
and 
val1 gt val2
are equivalent.
Greater Than Or Equal To The usual >= operator can be used as well as the abbreviation ge. For example 
val1 >= val2
and 
val1 ge val2
are equivalent.
Addition The usual + operator is used. For example 
val1 + val2
Subtraction The usual - operator is used. For example 
val1 - val2
Multiplication The usual * operator is used. For example 
val1 * val2
Division The usual / operator is used. For example 
val1 / val2
Integer Division The div operator is used. For example 
4 div 3
gives 1.
Modulus (or remainder) The % operator is used. An alternative is the mod operator. For example 
5 mod 2
gives 1 and is equivalent to 
5 % 2
Negation The unary - operator is used. For example 
-12
Array access Array elements may be accessed using either square brackets or a dotted numeral, e.g. 
arr1[0]
and 
arr1.0
are equivalent