hashmap_hashset_internals.java

import java.util.HashMap;
import java.util.HashSet;

public class Main {
    public static void main(String[] args) {
        Game ageOfEmpires = new Game("Age of Empires 2");

        HashMap<String, Game> gamesMap = new HashMap<>();
        gamesMap.put(ageOfEmpires.getName(), ageOfEmpires);
        gamesMap.get("Age of Empires 2");


        HashSet<Game> gamesSet = new HashSet<>();
        gamesSet.add(ageOfEmpires);
    }
}

class Game {
    private String name;

    public Game(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }
}