title: Realm RecyclerView, How to create header by day. or merge same day in one row
body: <p>i have a 3 variable in activities realm object</p>
  
  <pre><code>int id;
  String nameDay;
  String toDoActivities;
  </code></pre>
  
  <p>i using <code>OrderedRealmObject</code> and <code>realmResult</code> for my <code>realmrecyclerview</code>.</p>
  
  <p>this is my <code>onBindViewHolder</code>.</p>
  
  <pre><code>activities ac = activities.get(position);
  
  holder.txtDay.setText(activities.getNameDay);
  holder.txtToDo.setText(activities.getToDoActivities);
  </code></pre>
  
  <p>how to merge day if the day in realm is same. actually every day have more than 2 ToDoActivities.</p>