Magento2 Layout – Blank Page Issue

If your controller extend Magento\Framework\App\Action\Action you should follow rules of creation of the controller. So you should implement dependency injection of the parent class constructor (Magento\Framework\App\Action\Action):

/**
 * @param Context $context
 */
public function __construct(Context $context)
{
    parent::__construct($context);
    $this->_objectManager = $context->getObjectManager();
    $this->_eventManager = $context->getEventManager();
    $this->_url = $context->getUrl();
    $this->_actionFlag = $context->getActionFlag();
    $this->_redirect = $context->getRedirect();
    $this->_view = $context->getView();
    $this->messageManager = $context->getMessageManager();
}

Your construct method should look like this after a modifications:

/**
 * @param Context $context
 * @param UrlInterface $urlBuilder
 */
public function __construct(
    Context $context,
    UrlInterface $urlBuilder
) {
    parent::__construct($context);
    $this->urlBuilder = $urlBuilder;
}

NOTE: do not forget to remove old var/generation directory after implementing of modifications, because there are stored the generated files of controllers.

protected $formKey;   
protected $cart;
protected $product;

public function __construct(
\Magento\Framework\App\Action\Context $context,
\Magento\Framework\Data\Form\FormKey $formKey,
\Magento\Checkout\Model\Cart $cart,
\Magento\Catalog\Model\Product $product,
array $data = []) {
    $this->formKey = $formKey;
    $this->cart = $cart;
    $this->product = $product;      
    parent::__construct($context);
}

public function execute()
 { 
  $productId =10;
  $params = array(
                'form_key' => $this->formKey->getFormKey(),
                'product' => $productId, //product Id
                'qty'   =>1 //quantity of product                
            );              
    //Load the product based on productID   
    $_product = $this->product->load($productId);       
    $this->cart->addProduct($_product, $params);
    $this->cart->save();
 }