code: public void reverseInplace() {
      for (int i = 0; i < this.size / 2; i++) {
        boolean temp = this.elements[i];
        this.elements[i] = this.elements[this.size - i - 1];
        this.elements[this.size() - i - 1] = temp;
      }
    }
docs: Reverses the content of this vector in-place.