why did Joshua Bloch decrement the "size" value of stack in the pop method in effective java?

why did Joshua Bloch decrement the "size" value of stack in the pop method
in effective java?

here is the code from Item 6, pg 24, chapter 2 of effective java 2nd
edition, by Joshua Bloch. In the pop method he defines, he uses
elements[--size]. I am wondering why he used --size, instead
elements[size--] should return the same correct?
public class Stack {
private Object[] elements;
private int size = 0;
private static final int DEFAULT_INITIAL_CAPACITY = 16;
public Stack() {
elements = new Object[DEFAULT_INITIAL_CAPACITY];
}
public void push(Object e) {
ensureCapacity();
elements[size++] = e;
}
public Object pop() {
if (size == 0)
throw new EmptyStackException();
return elements[--size];
}
/**
* 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)
elements = Arrays.copyOf(elements, 2 * size + 1);
} }