title: switching between views
body: <p>I am trying to make my app view multiple views 
  I made 2 xml files (main, sub) 
  and I switch between them using :</p>
  
  <p>setContentView(R.Layout.main);</p>
  
  <p>setContentView(R.Layout.sub);</p>
  
  <p>When I switch to the sub, it switches fine. However, When I switch back to main, the app crashes and I have no clue why it did that. </p>
  
  <p>The only line that seems to make it crash is the calling of setContentView(R.Layout.main); for the second time.
  any clue on that ?</p>