Enumeration Interface's elements() method

Question

How the statement return new Enumeration() is possible, since Enumeration is an Interface. Plz explain. Thanks.

public Enumeration<E> elements() {
    return new Enumeration<E>() {
        int count = 0;

        public boolean hasMoreElements() {
            return count < elementCount;
        }

        public E nextElement() {
            synchronized (Vector.this) {
                if (count < elementCount) {
                    return elementData(count++);
                }
            }
            throw new NoSuchElementException("Vector Enumeration");
        }
    };
}

possible duplicate of [How are Anonymous (inner) classes used in Java?](http://stackoverflow.com/questions/355167/how-are-anonymous-inner-classes-used-in-java) — Joe, Feb 14 '15 at 02:27

score 0 · Answer 1 · answered Feb 14 '15 at 02:02

It is possible because it implements the Enumeration interface through an anonymous inner class.

Interfaces are defined to be implemented, and the use of an anonymous inner class is simply a shortcut, that works the same way as when you instantiate an abstract class (you must implement the abstract methods). In this case, you must implement ALL of the interface methods.

Enumeration Interface's elements() method

1 Answers1