package effect.java.generics.item29;

import java.util.Arrays;

import java.util.EmptyStackException;

public class Stack<E> {

private E[] elements;

private int size = 0;

private static final int DEFAULT_INITIAL_CAPACITY = 16;

@SuppressWarnings("unchecked")

public Stack() {

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;

return result;

}

private void ensureCapacity() {

if(elements.length == size) {

elements = Arrays.copyOf(elements, 2 * size + 1);

}

}

public boolean isEmpty() {

return size == 0;

}

public static void main(String[] args) {

Stack <String> stack = new Stack<>();

for(String arg: args) {

stack.push(arg);

}

while(!stack.isEmpty()) {

System.out.println(stack.pop().toUpperCase());

}

}

}