مشکل در نمایش صفحه

<?php
require("libs/Controller.php");
require("libs/view.php");
require("libs/Bootstrap.php");
$app = new Bootstrap();
?>

<?php
class Bootstrap{
    
        function __construct()
    {
        if(!isset($_GET['url']))
        {
            $url = 'index';
        }
        else
        {
            $url = $_GET['url'];
        }
        
        $url = explode('/', $url);
        //print_r($url);
        
        if(!file_exists("Controllers/".$url[0].".php"))
        {
            echo "Not Found Page";
        }else{
            $file="Controllers/".$url[0].".php";
            require($file);
            $controller=new $url[0]();
            }
        }
    }
?>

<?php
class Index extends Controller
{
function __construct()
{
    parent::__construct();
    //echo "<br>Page Index ";
    $this->view->Render("Index/index");
}
}
?>