title: method get(int) is undefined for the type Set
body: <p>I have written a piece of logic, where, my goal is to select random keys from the map. The map has been assigned as a <code>ConcurrentSkipListMap&lt;Text,IntWritable&gt; tuples</code>. Also, I don't have any industrial level experience with Java, so struggling to get over this.</p>
  
  <p>The piece of code is </p>
  
  <pre><code>Set&lt;Text&gt; keys = tuples.keySet();
  String randomKeys = keys.get(random.netInt(keys.size()))
  </code></pre>
  
  <p>I am not able to figure out the error statement: <code>method get(int) is undefined for the type Set&lt;Text&gt;</code></p>
  
  <p>Also, I have searched for the similar problem, and a solution do exist using <code>List</code>, but my key/value pairs are stored as <code>ConcurrentSkipListMap</code>, so not able to figure out this.</p>
  
  <p>Thanks.</p>