Finding all of the matching substrings, not only the “most extended” one

Question

The code

String s = \"y z a a a b c c z\";
Pattern p = Pattern.compile(\"(a )+(b )+(c *)c\");
Matcher m = p.matcher(s);
while (m.find()) {
    System.out.pri         


        

Answer 1

Given these very specific constraints (i.e. this is not a general case solution), this will work:

import java.util.Set;
import java.util.TreeSet;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class test {

    public static void main(String[] args) {

        String s = "y z a a a b c c z";

        Pattern p = Pattern.compile("(a )+(b )+(c ?)+");
        Set set = recurse(s, p, 0);
    }

    public static Set recurse(String s, Pattern p, int depth) {
        int temp = depth;
        while(temp>0) {
            System.out.print("  ");
            temp--;
        }
        System.out.println("-> " +s);

        Matcher matcher = p.matcher(s);
        Set set = new TreeSet();

        if(matcher.find()) {
            String found = matcher.group().trim();
            set.add(found);
            set.addAll(recurse(found.substring(1), p, depth+1));
            set.addAll(recurse(found.substring(0, found.length()-1), p, depth+1));
        }

        while(depth>0) {
            System.out.print("  ");
            depth--;
        }
        System.out.println("<- " +s);
        return set;
    }
}

I'm reasonably sure you can adapt it to work on other cases, but the recursion into the matched string means that overlapping matches (like the one pointed out by @ahenderson) won't work.