Class of shopping Cart for studies

Cart Class

<?php

require './KeyNotFoundException.php';

class Cart{

    protected $item;

    public function __construct() {
        $this->item = [];
    }

    public function addItem($idItem, array $itemsOptions = array()) {
        $this->item[$idItem] = $itemsOptions;
    }

    public function updateItem($idItem, array $arrayOptionsToUpdate = array()) {
        foreach ($arrayOptionsToUpdate as $key => $value) {
            $this->item[$idItem][$key] = $value;
        }
    }
    
    public function removeItem($idItem){
        unset($this->item[$idItem]);
    }

    public function getItem($id) {
        return (isset($this->item[$id]) ? $this->item[$id] : $this->fireException('KeyNotFoundException'));
    }

    public function getItems() {
        return $this->item;
    }
    
    public function getItemsFormattedArray(){
        var_dump($this->item);
    }

    private function fireException($exception) {
        switch ($exception) {
            case 'KeyNotFoundException':
                throw new KeyNotFoundException('Não existe este item no array', 1);
                break;
        }
    }

}

?>

KeyNotFoundException Class

<?php

class KeyNotFoundException extends Exception {

    public function __construct($message, $code) {
        parent::__construct($message, $code);
    }

    /* Representação do objeto personalizada no formato string */

    public function __toString() {
        return __CLASS__ . ": [{$this->code}]: {$this->message}\n";
    }

}

?>