Magento 2 Fatal error: Call to a member function getAttributeText() on string
<p>Fatal error: Call to a member function getAttributeText() on string in/opt/lampp/htdocs/magento2_new/Sourcecode/app/design/frontend/Emthemes/em0150jewelry/jewelry/Magento_Catalog/templates/product/list.phtml on line 539.This error occured by using a function 
<code>$optionText=$_product-&gt;getId()-&gt;getAttributeText('Farben');</code>
How can I resolve this in magento 2?</p>