title: kotlin add elements in array as sections
body: <p>Can anyone teach me how to initiate/add items in array as section? 
  something like - array[["john"],["daniel"],["jane"]]
  tried a few like <code>var d = ArrayList&lt;CustomClass&gt;(arrayListOf&lt;CustomClass&gt;())</code>
  that does not work. 
  for example, if i add "david" i want it look like array[["john"],["daniel", "david"],[“keith"]] by finding the index of array contains letter "d"</p>
  
  <p>how can i display them on a custom base adapter / listview? currently using a viewHolder</p>
  
  <pre><code>val viewHolder = ViewHolder(row.name) to display. 
  </code></pre>
  
  <p>Thanks!</p>