title: Android studio - new Activity with Fragment (XML files explanation)
body: <p>I want to create a new Activity in Android Studio with <code>MainActivity</code> as a parent. Although, when I create a blank activity (ex. <code>NewActivity</code>) with a fragment added I get the two expected classes<br>
  (<code>NewActivity</code> and <code>NewActivityFragment</code>) but when I check the layout resources, I can't understand why there are 3 XML files auto-generated and what's their meaning? </p>
  
  <ul>
  <li>What is the exact meaning of each XML-file generated ? The 3 XML files are the following : <strong>activity_new.xml</strong>, <strong>fragment_new.xml</strong> and <strong>content_new.xml</strong></li>
  </ul>
  
  <p>For example , if i want to add a <code>TextView</code> in the second activity, which XML file shall i modify?</p>