title: What is sjavac, who is it for and how do I use it?
body: <p>There has been <a href="https://www.google.co.uk/search?q=site:mail.openjdk.java.net+sjavac">some buzz</a> about a tool called <code>sjavac</code> on the OpenJDK mailing lists. Also, there are two related JEPs: <a href="http://openjdk.java.net/jeps/139">JEP 139: Enhance javac to Improve Build Speed</a> and <a href="http://openjdk.java.net/jeps/199">JEP 199: Smart Java Compilation, Phase Two</a>.</p>
  
  <p>My questions are:</p>
  
  <ul>
  <li>What exactly is the <code>sjavac</code> tool?</li>
  <li>Who is it intended for?</li>
  <li>How do I use it?</li>
  </ul>
  
  <p><sup><sub><em>Disclaimer: Self answered question. Just wanted to bring the knowledge of this tool to the StackOverflow community and to create a reference to future sjavac FAQ.</em></sub></sup></p>