HashSet的迭代器有问题

Klant

public class Klant {
    private int klantNummer;

    public Klant(int nummer) {
        this.klantNummer = nummer;
    }

    public int getKlantNummer() {
        return this.klantNummer;
    }
}

HashSet

public class MySet<Klant> { 
    private Collection<Klant> mySet = null;

    public MySet() {
        mySet=new HashSet<Klant>();
    }

    public void add(Klant elem) {
        mySet.add(elem);
    }

    public void toon() {
        Iterator<Klant> i = mySet.iterator();   
        while(i.hasNext()) {
            Klant k = i.next();
            System.out.println(k.);
        }
    }
}

toon()

<Klant>

k

Klant

getKlantNummer()

k

Object

Object k = (Klant)i.next();