Question

In the following Java code:

public static void main(String[] args) {
        String largeText = "abc myphrase. def";
        String phrase = "myphrase.";
        Pattern myPattern = Pattern.compile("\\b"+Pattern.quote(phrase)+"\\b");
        System.out.println("Pattern: "+myPattern);
        Matcher myMatcher = myPattern.matcher( largeText );
        boolean found = false;
        while(myMatcher.find()) {
          System.out.println("Found: "+myMatcher.group());
          found = true;
        }
        if(!found){
            System.out.println("Not found!");
        }
}

I get this output:

Pattern: \b\Qmyphrase.\E\b
Not found!

Please, can someone explain me why the above pattern does not produce a match? I do have a match if I use “myphrase” instead of “myphrase.” in the pattern.

Thank you for your help.

Answer 1

There is no boundary after the . A boundary occurs between a word character and a non-word character. Since both . and " " (space) are non-word characters there is no boundary between them.

If you use “myphase” in your pattern you get a match because there is a boundary between the word character e and the ..