Writing Scripts in Nashorn - Scripting in Java: Integrating with Groovy and JavaScript - page 153

var pattern = /Java/; // A non-global pattern
var text = "Java and JavaScript are not the same";

var result;

/* Do not use this loop. It will run forever because
pattern is non-global.
*/
while((result = pattern.exec(text)) !== null) {
// Code goes here
}

Some characters when used in certain contexts have special meaning. These
characters are known as metacharacters and they are (, ) , [ , ] , { , } , \ , ^ , $ , | , ? , * , + , and
the dot. I will discuss the special meanings of these characters at appropriate places in
this section.
In a regular expression, a set of characters enclosed within a pair of brackets is known
as a character class. The regular expression will match any of the characters in the set.
For example, /[abc]/ will match a , b , or c in the input text. You can also specify a range of
characters using a character class. The range is expressed using a hyphen. For example,
[a-z] represents any lowercase English letters; [0-9] represents any digit between 0 and 9.
If you use the character ^ in the beginning of a character class, it means complement
(meaning not). For example, [^abc] means any character except a , b , and c . The character
class [^a-z] represents any character except lowercase English letters. If you use the
character ^ anywhere in a character class, except in the beginning, it loses the special
meaning and it matches just a ^ character. For example, [abc^] will match a , b , c , or ^ .
Character classes also support multiple ranges and operations such as union, intersection,
subtraction on those ranges. Table 4-18 shows a few examples of using ranges in character
classes. Nashorn has some predefined character classes as listed in Table 4-19 .

Table 4-18. A Few Examples of Character Classes

Character Classes Meaning Category

[abc] Character a , b, or c Simple character class

[^xyz] A character except x , y, and z Complement or negation

[a-p] Characters a through p Range

[a-cx-z] Characters a through c , or x through z ,

which would include a , b , c , x , y , or z .

Union

[0-9&&[4-8]] Intersection of two ranges ( 4 , 5 , 6 , 7 , or 8 ) Intersection

[a-z&&[^aeiou]] All lowercase letters minus vowels. In

other words, a lowercase letter that
is not a vowel. That is, all lowercase
consonants.

Subtraction