title: how to select all check boxes in RecyclerView by clicking Button?
body: <p>This code in <code>onclick</code> of the Button in Activity:</p>
  
  <pre><code>if(v.getId()==recomendationSelectAllFriends.getId()){
      recomendationAdapter.selectAll(resultEntities.size());
  }
  </code></pre>
  
  <p>This method in Adapter:</p>
  
  <pre><code>public void selectAll(int size){
     // what should be written here?
  }
  </code></pre>