CODEWITHSUNDEEP
javaregexloopspattern-matching
SophieM
SophieM

Reputation: 223

java regex multiple patterns sequential matching

I have a specific question, to which I couldn't find any answer online. Basically, I would like to run a pattern-matching operation on a text, with multiple patterns. However, I do not wish that the matcher gets me the result all at once, but instead that each pattern is called at different stages of the loop, at the same time that specific operations are performed on each of these stages. So for instance, imagining I have Pattern1, Pattern2, and Pattern3, I would like something like:

 if (Pattern 1 = true) {
        delete Pattern1;
    } else if (Pattern 2 = true) {
        delete Pattern2;
    } else if (Pattern 3 = true) {
        replace with 'something;
    } .....and so on

(this is just an illustration of the loop, so probably the syntax is not correct, )

My question is then: how can I compile different patterns, while calling them separately? (I've only seen multiple patterns compiled together and searched together with the help of AND/OR and so on..that's not what I'm looking for unfortunately) Could I save the patterns in an array and call each of them on my loop?

Upvotes: 2

Views: 2433

Answers (2)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726779

You can make a common interface, and make anonymous implementations that use patterns or whatever else you may want to transform your strings:

interface StringProcessor {
    String process(String source);
}

StringProcessor[] processors = new StringProcessor[] {
    new StringProcessor() {
        private final Pattern p = Pattern.compile("[0-9]+");
        public String process(String source) {
            String res = source;
            if (p.matcher(source).find()) {
                res = ... // delete
            }
            return res;
        }
    }
,   new StringProcessor() {
        private final Pattern p = Pattern.compile("[a-z]+");
        public String process(String source) {
            String res = source;
            if (p.matcher(source).find()) {
                res = ... // replace
            }
            return res;
        }
    }
,   new StringProcessor() {
        private final Pattern p = Pattern.compile("[%^#@]{2,5}");
        public String process(String source) {
            String res = source;
            if (p.matcher(source).find()) {
                res = ... // do whatever else
            }
            return res;
        }
    }
};

String res = "My starting string 123 and more 456";
for (StringProcessor p : processors) {
    res = p.process(res);
}

Note that implementations of StringProcessor.process do not need to use regular expressions at all. The loop at the bottom has no idea the regexp is involved in obtaining the results.

Upvotes: 1

Ivan Borisov
Ivan Borisov

Reputation: 413

Prepare your Pattern objects pattern1, pattern2, pattern3 and store them at any container (array or list). Then loop over this container using usePattern(Pattern newPattern) method of Matcher object at each iteration.

Upvotes: 2

Related Questions