Generic method that extends Comparable and gets a Generic Data Structure type

Question

I have a generic class that implements a "Set" using ArrayList:

public class MySet<E> {
    ArrayList <E> setList;
    public MySet(){
        this.setList =  new ArrayList<E>();
    }
    public MySet(E[] inputArray){
        this();
        for(E element: inputArray)
            insert( element);
    }
    ...

Now i have another Class "Person.java" that have properties of "age","name","ID"..

Lets say i make an array of Person[] and make an object of type set from that array:

Person p1 = new Person("dani",15,12344);
Person p2 = new Person("michal",24,12354);
Person p3 = new Person("Leah",22,18888);
Person[] PeopleArr = {p1,p2,p3};
MySet<Person> People = new  MySet<Person>(PeopleArr);

And now i want to make a generic method in Person that gets a type of MySet and returns an object of type Person that have the minimal age. How do i iterate through such thing?

I know that when passing an array its not a problem:

public static <E extends Comparable<Person> > E min (E[] array) { 
    if (array == null || array.length ==0) return null;
    E min = array[0];
    for(int i=0;i<array.length;i++){
        if(array[i].compareTo((Person) min) <0) min = array[i];
    }
    return min;
}
public int compareTo(Object persona) {
    // TODO Auto-generated method stub
    Person person = (Person) persona;
    if (this.age == person.age)
        return 0;
    else if(this.age < person.age)
        return -1;
    return 1;
}

But i want the signature to be:

public static <E extends Comparable<Person> > E min (MySet<Person> set) 

Any ideas how? (Its not possible to cast from MySet to ArrayList) Iterator seems like the only way but no idea how to compare the values

Thank you!!!

Answer 1

Implement Iterable interface in MySet class:

public class MySet<E> implements Iterable<E> {
    ...
    public Iterator<E> iterator() {
        return setList.iterator();
    }
}

Now you can iterate over MySet items:

for (Person person : set) {
}