/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.util.regex.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		var input = Arrays.asList("d", "a", "y / a", "a / z", "b / a / c", "a / c / a");
	    Comparator<String> comparator = Comparator.comparingInt((String s) -> countMatches(s, "/"))
	                                              .thenComparing(Comparator.naturalOrder());
	    input.stream().sorted(comparator).forEach(System.out::println);
	}
 
	private static int countMatches(String text, String what) {
		var matcher = Pattern.compile(what).matcher(text);
		var count = 0;
		while (matcher.find()) count++;
		return count;
	}
}

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

YS9iIAphL2IvYy8KYWJjZA==

a/b 
a/b/c/
abcd