title: Android application with more than one screen
body: <p>I'm currently trying to develop an android application in eclipse(java) which shows some jokes downloaded from a database. The user is able to vote on each joke once, and to make sure they only do that once, I have made a table in the database that contains three columns. </p>
  
  <ul>
  <li>E-mail</li>
  <li>Username (Used when a user publishes a joke)</li>
  <li>Encrypted Password</li>
  </ul>
  
  <p>I have two "screens" right now:</p>
  
  <ul>
  <li>Login screen</li>
  <li>Main screen</li>
  </ul>
  
  <p>At every single start up the application checks the SharedPreferences for a file containing some information, and if there is some information it should load the Main screen, but if there is no account information the  Login screen should be loaded.</p>
  
  <p>Any idea on how I can use different screens, and how should it be coded?</p>