title: How to use non-standard (hidden) API classes?
body: <p>I'm fairly new to Android and have gone through the basic tutorials.  I thought I'd dig a little deeper and downloaded the source code to some of the "native" Android apps, like IM, Email, Voice Dialer, etc.</p>
  
  <p>In importing the source of these native apps into Eclipse, I found that they reference classes that are not in the 2.1 API, i.e. classes such as android.content.Entity, android.net.http.DomainNameChecker, etc.  As a result, I can't compile and play with this code.</p>
  
  <p>So is there is a "hidden" API that the native apps use that is not available to the regular app developers?  Is there a "native" SDK I can use to import these classes?</p>
  
  <p>David</p>