title: Why is there not a concurrent TreeMap?
body: <p>I have a few question related to <code>java.util.concurrent</code> package:</p>
  
  <ol>
  <li><p>Why in the java API there is the non-concurrent <a href="http://docs.oracle.com/javase/1.5.0/docs/api/java/util/TreeMap.html" rel="noreferrer">TreeMap</a> on one side and the concurrent  <a href="https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentSkipListMap.html" rel="noreferrer">ConcurrentSkipListMap</a> on one other?</p></li>
  <li><p>Why did not they call it <code>ConcurrentTreeMap</code>? Is it safe to say that a <code>SkipListMap</code> includes a <code>TreeMap</code>?</p></li>
  </ol>
  
  <p>For example a non concurrent <code>HashMap</code> has got its concurrent counterpart <code>ConcurrentHashMap</code>. Why does it not happen for the <code>TreeMap</code>?</p>