An implementation of a stack in java ... but with a bug in it

Stack.java

import java.util.*;

public class Stack {
    private Object[] elements;
    private int size = 0;

    public Stack(int initialCapacity) {
        this.elements = new Object[initialCapacity];
     }
 
     public void push(Object e) {
         ensureCapacity();
         elements[size++] = e;
     }
 
     public Object pop() {
         if (size==0)
             throw new EmptyStackException();
         Object result = elements[--size];
         return result;
     }
 
     /**
      * Ensure space for at least one more element, roughly
      * doubling the capacity each time the array needs to grow.
      */
     private void ensureCapacity() {
         if (elements.length == size) {
             Object[] oldElements = elements;
             elements = new Object[2 * elements.length + 1];
             System.arraycopy(oldElements, 0, elements, 0, size);
         }
     }
 
     public static void main(String[] args) {
         Stack s = new Stack(0);
         for (int i=0; i < args.length; i++)
             s.push(args[i]);
         for (int i=0; i < args.length; i++)
             System.out.println(s.pop());
     }
 }