JF-Maps-Exercise-06.Courses

package com.company;

import java.util.*;

public class Courses {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        Map<String, List<String>> usersList = new LinkedHashMap<>();

        String input = sc.nextLine();

        while (!input.toLowerCase().equals("end")) {
            String[] tokens = input.split("\\s:\\s");
            String courseName = tokens[0];
            String user = tokens[1];
            int counter = 0;

            if (usersList.containsKey(courseName)) {
                usersList.get(courseName).add(user);

            } else {
                usersList.put(courseName, new ArrayList<>());
                usersList.get(courseName).add(user);
            }

            input = sc.nextLine();
        }

        usersList.entrySet().stream().sorted((e1, e2) -> Integer.compare(e2.getValue().size(), e1.getValue().size()))
                .forEach(e -> {
                    System.out.println(String.format("%s: %d", e.getKey(), e.getValue().size()));
                    Collections.sort(e.getValue());
                    e.getValue().forEach(a -> System.out.println("-- " + a));
                });

    }
}