private function swapPagePositions(Page $firstPage, Page $secondPage) { $firstPage->setPosition($firstPage->getPosition() + $secondPage->getPosition()); $secondPage->setPosition($firstPage->getPosition() - $secondPage->getPosition()); $firstPage->setPosition($firstPage->getPosition() - $secondPage->getPosition()); $this->pageDao->update($firstPage); $this->pageDao->update($secondPage); }