title: array list saved in pref, load each item only once
body: <p>I need to store a list of URLs, in pref. </p>
  
  <pre><code>[www.url1.com, www.url2.com, www.url3.com, www.url4.com, ]
  </code></pre>
  
  <p>I want to know how can I call the list array, and load each item only once. I.e. if item 1 been loaded, then mark as done. next time I call the list I get item 2.</p>
  
  <p>There reason why I ask is:</p>
  
  <p>I need to build a video player playList. </p>
  
  <p>I will build a playList array and store all the URLs.</p>
  
  <p>when the player activity start it will load url1, when this clip finish, it will load a splash activity for 5 seconds and then call the player activity again. (this time it has to load the url 2).</p>
  
  <p>In the end, after all the urls have been played. I need to store analytic as successfully playlist.</p>
  
  <p>The part I don't know how to handle is the PlayList. and how to load in order only one URL once.</p>
  
  <p>Any feed back will be very helpful, I really appreciate your hep. thank.</p>