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Thread: Need help with Regex

  1. #1
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    Default Need help with Regex

    Does anyone know how to use regex to capture patterns?

    I am coming from many years of php background, in php its pretty much straight forward preg_match($pattern, $subject, $matches);
    and then you get all your matches in the $matches array

    How do I do somethink like that in Java?
    Let's say I want to capture words
    'truck' and 'old' from the string "old man trucking in an old truck'
    What I need it to get back array or set with words 'truck' and 'old' but not trucking
    I would use the \w modifier to make sure I capture on word boundries

    Can anyone help me here?


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    Administrator copeg's Avatar
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    Default Re: Need help with Regex

    See Lesson: Regular Expressions (The Java™ Tutorials > Essential Classes). The String class offers a few functions to replace and match using regular expressions, but capturing groups is best done using a Pattern and Matcher class described in the above link.

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    Default Re: Need help with Regex

    The OP probably doesn't need it, but for reference of others who happen by this thread when searching for help with regex: another very good learning resource is
    Regular-Expressions.info - Regex Tutorial, Examples and Reference - Regexp Patterns

    db

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    Default Re: Need help with Regex

    Thanks. I figured out how to use Pattern and Matcher. It's a lot more involved than in PHP
    I find that extracting matches based on regex is the easiest in php, slightly more code required in Javascript and even more code required in Java.

    This is sample of my test code:
    String text = "Some text about cats, dogs, cat and dog and another *cat*";
    Pattern pattern;
    TreeSet<String> matches = new TreeSet<String>();
    pattern = Pattern.compile("\\bcat\\b|\\bdog\\b", Pattern.CASE_INSENSITIVE);
    		Matcher matcher = pattern.matcher(text);
    		while (matcher.find()) {
    			System.out.println("found it");
    			matches.add(matcher.group());
    		}
     
    		for (String m : matches) {
    			System.out.println("Found: " + (String) m);
    		}

    By using TreeSet I am filtering out duplicates.
    I wonder what do you, experienced Java programmer think? Is this about the right way to collect matches or is there an easier way out there?

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    Default Re: Need help with Regex

    Take a look at this link - http://www.javaprogrammingforums.com...explained.html
    Please use [highlight=Java] code [/highlight] tags when posting your code.
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