title: The import android.os cannot be resolved
body: <p>I recently created a bug-free, fulling functioning android project. I even tested it on an android device, it worked fine. </p>
  
  <p>I then closed eclipse and installed a few things from the SDK manager intended to speed up my emulator (intel x86 atom system image). After the downloads finished I opened eclipse and had errors on almost every line of my previously fine code. </p>
  
  <p>It didn't recognize any of the android imports (hence the title). I couldn't open the android SDK manager because of: </p>
  
  <p><code>"Location of the Android SDK Manager has not been set up in the preferences."</code></p>
  
  <p>Then, after a bit more poking around a window popped up saying:</p>
  
  <p><code>"Multiple errors have occurred. java.lang.NullPointerException"</code>. </p>
  
  <p>The XML doesn't have any error warnings, but the graphical display window is blank and at the bottom it says:</p>
  
  <p><code>"Eclipse is loading the SDK.  new_page.xml will refresh automatically once the process is finished."</code></p>
  
  <p>(its not loading anything, it has been that way for about an hour). I tried cleaning and rebuilding the project to no avail. I can't post pictures for some reason, my apologies. Some advice would be greatly appreciated! TLDR: I updated with the android SDKmanager and now nothing works!</p>