Hola nois :-)

Varies maneres de recorrer collections:

Iterator<Book> version:
	Iterator<Book> it = llista.iterator();
	while(it.hasNext()){
		Book b = it.next();
		if(b.GetIsbn().equals(comanda[1])){
			System.out.println(b);
			break;
		}
	}

Iterator version (casting required):
	Iterator it = llista.iterator();
	while(it.hasNext()){
		Book b = (Book) it.next();
		if(b.GetIsbn().equals(comanda[1])){
			System.out.println(b);
			break;
		}
	}

Enhanced for for lists and sets:
	for(Book b : set)

If it's a map:
	for(Book b : map.values())
	for(String isbn : map.keys())
	for(Map.Entry<String, Book> entry : map.entrySet())

Iterator for map entry:
	Map<Integer, Integer> map = new HashMap<Integer, Integer>();
	for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
		System.out.println("Key = " + entry.getKey() +
			", Value = " + entry.getValue());
	}

You can also iterate for map.keySet() or map.values():
	for (Integer k : map.keySet())
	for (Integer v : map.values())

To use TreeSet<Dog>, Dog has to be Comparable.
To use MapSet<Key,Dog>, Key has to be Comparable.

class Dog implements Comparable<Dog>{
	String color;
	int size;

	[...]
 
	@Override
	public int compareTo(Dog o) {
		return  o.size - this.size;
	}
}

Salut,

Manel