Java Regex Word Boundaries

Question

Hi I have the following code which is meant to find the word "is" but not when it is within another string so the word "this" should not return a match so I use \b. But the following code does not find a match and I cant figure out why?

public static void main(String[] args) {
    String a = "This island is beautiful.";
    Pattern p = Pattern.compile("\bis\b");
    Matcher m = p.matcher(a);

    while(m.find()){

        System.out.println(a.substring(m.start(), m.end()));
    }

}

Instead of a.substring(m.start(), m.end()) you could just write m.group(). — Keppil
– Keppil, Commented Jan 27, 2014 at 19:47

anubhava · Accepted Answer · 2014-01-27 19:29:55Z

14

Double escape it:

Pattern p = Pattern.compile("\\bis\\b");

Regex in Java requires you to doubly escape certain special regex symbols, one escaping for Java and another for underlying regex engine.

answered Jan 27, 2014 at 19:29

anubhava

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2 Comments

anubhava Over a year ago

No need to be since \b doesn't generate compile time error as \s or \w etc.

user557597 Over a year ago

He already had the word boundry, just needed to escape the escape for a double quoted string.

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