import java.util.regex.*;
import java.util.*;
import java.util.stream.*; //Collectors
 
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		String regex = "cgcg";
		Pattern pattern = Pattern.compile("(?=(" + regex + "))");
		Matcher matcher = pattern.matcher("cgcgcgcgcgcg");
		while (matcher.find())
		    System.out.println(matcher.start(1));
 
        List<Integer> results = pattern.matcher("cgcgcgcgcgcg")
            .results()
            .map(r -> r.start(1))
            .collect(Collectors.toList());
        System.out.println(results); 
	}
}

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