Question

I’ve this exercise with an algorithm to implement. I have this main:

    public static void main(String[] args) {
        Person a = new Person("Tony");
        Person c = new Person("Luke");
        Person o = new Person("Ann");

        a.addFriends(c);
        a.addFriends(o);

        for(Person p: a.contacts())
            System.out.println(p);
}

If I replace “a.contacts()” with “a” and use this class, the code works! But How can I implement the for-each loop with “a.contacts()”?? Thanks

class Person implements Iterable<Person> {

    private Set<Person> friends = new HashSet<Person>();   
    private String name;

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

    public void addFriends(Person o){                
        friends.add(o);
   }

    public String toString(){
        return this.name;
    }


    @Override
    public Iterator<Person> iterator() {
        Iterator<Person> i = friends.iterator();
        return i;
    }

    //Here the contacts method to implement!!

}

Answer 1

Since you want to run a loop for Person so the place next to : should be a collection of type Person.

    for(Person p: a.contacts())
        System.out.println(p);

You could either choose a List or Set for this and return the collection from contacts() method of class Person.

In this case since you’ve have Set so return it.

public Set<Person> contacts() {
    return friends;
}