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, Jan 27 '14 at 19:47

score 14 · Accepted Answer · answered Jan 27 '14 at 19:29

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 '14 at 19:29

anubhava

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No need to be since `\b` doesn't generate compile time error as `\s` or `\w` etc. – anubhava Jan 27 '14 at 19:33
He already had the word boundry, just needed to escape the escape for a double quoted string. – Jan 27 '14 at 19:36

Java Regex Word Boundaries

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