package org.effectivejava.examples.chapter05.item28;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
public class <E> {
	private E[] elements;
	private int size = 0;
	private static final int DEFAULT_INITIAL_CAPACITY = 16;
	("unchecked")
	public () {
		elements = (E[]) new Object[DEFAULT_INITIAL_CAPACITY];
	}
	public void push(E e) {
		ensureCapacity();
		elements[size++] = e;
	}
	public E pop() {
		if (size == 0)
			throw new EmptyStackException();
		E result = elements[--size];
		elements[size] = null; // Eliminate obsolete reference
		return result;
	}
	// pushAll method without wildcard type - deficient!
	// public void pushAll(Iterable<E> src) {
	// for (E e : src)
	// push(e);
	// }
	// Wildcard type for parameter that serves as an E producer
	public void pushAll(Iterable<? extends E> src) {
		for (E e : src)
			push(e);
	}
	// popAll method without wildcard type - deficient!
	// public void popAll(Collection<E> dst) {
	// while (!isEmpty())
	// dst.add(pop());
	// }
	// Wildcard type for parameter that serves as an E consumer
	public void popAll(Collection<? super E> dst) {
		while (!isEmpty())
			dst.add(pop());
	}
  
 	public static void main(String[] args) {
		Stack<Number> numberStack = new Stack<Number>();
		Iterable<Integer> integers = Arrays.asList(3, 1, 4, 1, 5, 9);
		numberStack.pushAll(integers);
		Collection<Object> objects = new ArrayList<Object>();
		numberStack.popAll(objects);
	}
}

public class Favorites {
	// Typesafe heterogeneous container pattern - implementation
	private Map<Class<?>, Object> favorites = new HashMap<Class<?>, Object>();
	public <T> void putFavorite(Class<T> type, T instance) {
		if (type == null)
			throw new NullPointerException("Type is null");
		favorites.put(type, instance);
	}
	public <T> T getFavorite(Class<T> type) {
		return type.cast(favorites.get(type));
	}
}