Question

A common approach to create an Iterator is :

Iterator iter = myarray.iterator(); 

Can anybody tell me how iter is created without new operator?
I know Iterator is an interface, so who implements it?

Answer 1

If you look inside the implementation of iterator(), there’ll be a new inside there, somewhere. For example, this is the iterator() method from OpenJDK’s ArrayList:

public Iterator<E> iterator() {
    return new Itr();
}

In turn, Itr refers to a private inner class that implements the Iterator interface:

private class Itr implements Iterator<E> {
    // implementation details
}