Thread: return type of iterator() method

Originally Posted by msnishan

what does the iterator() method return???it can't return an object of Iterator as it's an interface...

Exactly! Iterator is an interface. All standard collections in the framework (and in general any type that implements Iterable) return an implementation of Iterator. Typically this implementation is realized with an internal class (typically an "inner class", regular or anonymous) that is generally not visible outside the class of the collection.

So an iterator() method is typically constructed in a similar way like this:

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

or with anonymous inner class:

public Iterator<E> iterator() {
    return new Iterator() {
        //......implementation of hasNext/next/remove methods .....
    };
}