JAVA Push and Pop array.java

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);
  }
}

return elements[--size] at line 18 will return last element but we are not poping elements, element size still same, we need set last element to null