How to add an specific action button in views?
Here is the solution I found for my problem:
Let say that my entity is named Entity.
I created a new operation in my controller implementing my business logic ,  say we'll call it operation_name.
Then, in my EntityListBuilder.php , I surcharged the operation getDefaultOperations, specifying the name of my operation, the url and title :

 public function getDefaultOperations(EntityInterface $entity) {
    $operations = parent::getDefaultOperations($entity);
    $operations['operation_name'] = array(
        'title' =&gt; $this-&gt;t('operation_title'),
        'weight' =&gt; 30,
        'url' =&gt; new Url('url',array(
          'medecin' =&gt; $entity-&gt;id(),
          )
        )
      );
      return  $operations;
    }

Back to my view configuration: In adding fields section I will add "Action link" , we will notice that the operation "operation_name" was add to the others (edit and delete).