What is the difference between the Set<> and Map<> interfaces? [closed]

The difference is the functionality defined for each of these interfaces:

• Mapis an interface that defines storing objects in pairs of type Key (or Key) Value, where you can register, get and remove an element from the Key.

  Example:

  //creamos el mapa
  Map<String, Usuario> mapa = new HashMap<>();
  //agregamos elementos al mapa
  mapa.put("Luiggi Mendoza J", new Usuario(227, "Luiggi Mendoza J", 10.4k));
  mapa.put("theboshy", new Usuario(9206, "theboshy", 1));
  System.out.println(mapa.get("theboshy")); //imprime datos de usuario
  System.out.println(mapa.get("elporfirio")); //imprime nulo
  //recorrer todas las entradas llave-valor del mapa
  //e imprimir la llave y el valor correspondiente
  for (Map.Entry<String, Usuario> entry : mapa.entrySet()) {
      System.out.printf(
          "Llave: %s. Valor: %s\n",
          entry.getKey(), entry.getValue());
  }
  

  There can only be 1 Value associated with a Key. This does not mean that there can be 1 Value associated with multiple Keys. Example:

  Map<String, String> mapa = new HashMap<>();
  mapa.put("saludo", "hola mundo");
  System.out.println(mapa.get("saludo")); //imprime 'hola mundo'
  String valor = "aloha!";
  //reemplazamos el valor de la llave "saludo"
  mapa.put("saludo", valor);
  System.out.println(mapa.get("saludo")); //imprime 'aloha!'
  //asignamos el mismo valor a una nueva llave
  mapa.put("saludo efusivo", valor);
  System.out.println(mapa.get("saludo"));
  System.out.println(mapa.get("saludo efusivo"));
  //ambas sentencias imprimieros 'aloha!'
  

• Setis an interface that defines storing objects as if it were a mathematical set. This allows elements to be registered and removed from this set, but it does not allow them to be obtained one by one. Setit is mainly used to check that there are no duplicate objects in a collection.

  Example:

  Set<Integer> set = new HashSet<>();
  //agregamos elementos
  set.add(10);
  set.add(5);
  set.add(8);
  //podemos remover elementos
  set.remove(10);
  //pero no podemos obtener elementos, no existe un método `get`
  //lo que si, existe un método `contains` que permite verificar
  //si un elemento existe en el set
  if (set.contains(5)) {
      System.out.println("5 existe");
  }
  //sin embargo, se pueden recorrer todos los elementos de un set
  for (Integer elem : set) {
      System.out.println(elem);
  }
  

  It should be noted that a Setcan be seen simply as a Map<Object, Boolean>, where the objects to be inserted into the Setare the keys of the Map. This can be checked by using the method Collections#newSetFromMap(Map<E, Boolean>).