/**
* An iterator over a collection. Iterator takes the place of
* Enumeration in the Java collections framework. Iterators differ
* from enumerations in two ways:
*
* * Iterators allow the caller to remove elements from the underlying
*   collection during the iteration with well-defined semantics.
*  
* * Method names have been improved.
*
* This interface is a member of the Java Collections Framework.
*/
public interface Iterator<T> {
    /**
     * Returns true if the iteration has more elements.
     */
    boolean hasNext();

    /**
     * Returns the next element in the iteration.
     */
    T next();

    /**
     * Removes from the underlying collection the last element
     * returned by the iterator (optional operation).
     */
    void remove();
}

/**
* Implementing this interface allows an object to be the target of
* the "foreach" statement.
*/
public interface Iterable<T> {
    /**
     * Returns an iterator over a set of elements of type T.
     */
    Iterator<T> iterator();
}