title: changing fragment's place when user select a tab android
body: <p>I've an application where I use two fragments(the first for displaying a list, the other for text) and an actionBar.</p>
  
  <p>I want, when a user selects a certain item from the actionBar, to exchange the two fragments (the one displaying the list displays the text, and the other displays the list).</p>
  
  <p>thnks in advance.</p>