title: How to subtract two calendar object in Android
body: <p>Say for example I have two calendar object with the format of "MM/dd/yyyy". How do I subtract them and should return the number of days? For example, "9/7/2014" - "9/1/2014" and returns 7.</p>
  
  <pre><code>Calendar calendar = Calendar.getInstance();
  Calendar today = Calendar.getInstance();
  </code></pre>