title: Java Collection: what to convert Collection<List<String>> to ArrayList<List<String>> or List<List<String>>?
body: <p>I am using <code>Multimap&lt;String, List&lt;String&gt;&gt;</code> in one of my API's. Now to get all the values means list of list I used the <code>.values()</code> method of the multimap. But this method is returning me <code>Collection&lt;List&lt;String&gt;&gt;</code>. Now to play on the index on this collection I want to convert it into <code>List&lt;List&lt;String&gt;&gt;</code> or <code>ArrayList&lt;List&lt;String&gt;&gt;</code>. </p>
  
  <p>How to cast or convert without building new arrayList and explicit add list values from collections to that arraylist. </p>