title: R class missing after creating android project from existing source
body: <p>I downloaded the source for SpriteMethodTest, and I want to build it in Eclipse. So I Went:</p>
  
  <p>File >> New >> Android Project >> Create Project From Existing Source >> SpriteMethodTest</p>
  
  <p>It created the project alright, but the R class is not generated. Any file that references a resource in R says <code>R cannot be resolved</code>.</p>
  
  <p>Importing android.R just results in <code>R.drawable.background cannot be resolved</code>. How do I generate R again?</p>