#format java
/* Example of IteratorPattern
 */
import java.util.Vector;

interface Aggregate {
    public abstract Iterator iterator();
}

interface Iterator {
    public abstract boolean hasNext();
    public abstract Object next();
}

class Book {
    private String name = "";
    public Book(String name) {
        this.name = name;
    }
    public String getName() {
        return name;
    }
}

class BookShelf implements Aggregate {
    private Vector books;
    public BookShelf(int initialsize) {
        this.books = new Vector(initialsize);
    }
    public Book getBookAt(int index) {
        return (Book)books.get(index);
    }
    public void appendBook(Book book) {
        books.add(book);
    }
    public int getLength() {
        return books.size();
    }
    public Iterator iterator() {
        return new BookShelfIterator(this);
    }
}

class BookShelfIterator implements Iterator {
    private BookShelf bookShelf;
    private int index;
    public BookShelfIterator(BookShelf bookShelf) {
        this.bookShelf = bookShelf;
        this.index = 0;
    }
    public boolean hasNext() {
        if(index < bookShelf.getLength()) {
            return true;
        } else {
            return false;
        }
    }
    public Object next() {
        Book book = bookShelf.getBookAt(index);
        index++;
        return book;
    }
}

public class IteratorBookShelf {
    public static void main(String[] args) {
        BookShelf bookShelf = new BookShelf(4);
        bookShelf.appendBook(new Book("Around the World in 80 days"));
        bookShelf.appendBook(new Book("Bible"));
        bookShelf.appendBook(new Book("Cinderella"));
        bookShelf.appendBook(new Book("Daddy-Long-Legs"));
        Iterator it = bookShelf.iterator();
        while(it.hasNext()) {
            Book book = (Book)it.next();
            System.out.println(" "+book.getName());
        }
    }
}