title: How to generate R.java
body: <p>I downloaded few source codes from Google source codes.</p>
  
  <p>I executed them on Eclipse but <code>R.java</code> file is not created and therefore I got many errors saying that <code>R</code> cannot be resolved. There is no <code>main.xml</code> in layout too. Some other XML files are there. How can I execute these programs?</p>