03. Hero Recruitment

package ZadachiOtIzpita;

import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;

public class HeroRecruitment {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);


        Map<String, Set<String>> heroes = new LinkedHashMap<>();

        String input = scanner.nextLine();
        while (!input.equals("End")) {
            String[] tokens = input.split("\\s+");
            String command = tokens[0];
            String heroName = tokens[1];

            switch (command) {
                case "Enroll":
                    if (!heroes.containsKey(heroName)) {
                        heroes.put(heroName, new LinkedHashSet<>());
                    } else {
                        System.out.println(heroName + " is already enrolled.");
                    }
                    break;
                case "Learn":
                    String spellName = tokens[2];
                    if (heroes.containsKey(heroName)) {
                        if (!heroes.get(heroName).contains(spellName)) {
                            heroes.get(heroName).add(spellName);
                        } else {
                            System.out.println(heroName + " has already learnt " + spellName + ".");
                        }
                    } else {
                        System.out.println(heroName + " doesn't exist.");
                    }
                    break;
                case "Unlearn":
                    spellName = tokens[2];
                    if (heroes.containsKey(heroName)) {
                        if (heroes.get(heroName).contains(spellName)) {
                            heroes.get(heroName).remove(spellName);
                        } else {
                            System.out.println(heroName + " doesn't know " + spellName + ".");
                        }
                    } else {
                        System.out.println(heroName + " doesn't exist.");
                    }
                    break;
            }

            input = scanner.nextLine();
        }

        System.out.println("Heroes:");
        for (Map.Entry<String, Set<String>> entry : heroes.entrySet()) {
            System.out.print("== " + entry.getKey() + ": ");
            if (!entry.getValue().isEmpty()) {
                System.out.print(String.join(", ", entry.getValue()));
            }
            System.out.println();
        }
    }
}