import java.util.*;

// a class for iterating through the alphabet
class AlphabetIterator implements Iterator<Character> {
	// keeps track of which one we're on and whether we are uppercase or not
	private char current;
	private boolean upper;
	
	// starts out on a or A
	public AlphabetIterator(boolean uppercase) {
		if (uppercase) {
			current = 'A';
		} else {
			current = 'a';
		}
		upper = uppercase;
	}

	// returns whether we have a next value in the sequence
	@Override
	public boolean hasNext() {
		if (upper) {
			return current <= 'Z';
		} else {
			return current <= 'z';
		}
	}

	// returns the next one in the sequence
    @Override
	public Character next() {
		Character val = Character.valueOf(current);
		current++;
		return val;
	}
}

// this class implements Iterable using the Iterator
class Alphabet implements Iterable<Character> {
	private boolean uppercase;
	
	public Alphabet(boolean uppercase) {
		this.uppercase = uppercase;
	}

    // returns an iterator
	public Iterator<Character> iterator() {
		return new AlphabetIterator(uppercase);
	}
}

// we can now write code to the iterable interface itself
class Algorithms {
    // this method can be called on ArrayList, LinkedList or Alphabet
	public static int count(Iterable sequence) {
		int i = 0;
		// loop through using the iterator interface
		Iterator current = sequence.iterator();
		while (current.hasNext()) {
			i++;
			current.next();
		}
		return i;
	}
}

public class IteratorExample {
	public static void main(String args[]) {
		// make a capital alphabet
		Alphabet letters = new Alphabet(true);

		// count the letters
		System.out.printf("There are %d items in the alphabet:\n", Algorithms.count(letters));

		// the new style for loop also works using iterators under the hood
		for (Character c : letters) {
			System.out.println(c);
		}
	}
}