title: Source errors in eclipse
body: <p>When I create a new android project appearing red exclamation mark
  and when I tried to run the app the message say </p>
  
  <blockquote>
    <p>Android library projects cannot be launched</p>
  </blockquote>
  
  <p>From properties --- Android and unchecked the is library check box and unchecked but this solution not useful and the exclamation mark change to red X
  and this error </p>
  
  <blockquote>
    <p>Project 'appcompat_v7' is missing required source folder: 'gen'   resource appcompat_v7       location Build path </p>
  </blockquote>
  
  <p>this problem only in the source file</p>