title: RecyclerView provides fade in, fade out animations when item get added, deleted by default?
body: <p>I was learning about RecyclerView using online tutorials, youtube, and ebooks. I have found that <strong>By default, RecyclerView instantiates and uses an instance of DefaultItemAnimator</strong> So it provides animations for add, remove operations. </p>
  
  <p>But in AndroidHive, Slidenerd youtube channel and lot of other online sites, they use the below code.</p>
  
  <pre><code>recyclerView.setItemAnimator(new DefaultItemAnimator());
  </code></pre>
  
  <p>I didn't understand, why are they using the above code?</p>
  
  <ol>
  <li>Is there any need for using the above code?</li>
  <li>if yes, What doc means by default?</li>
  </ol>
  
  <p>I have searched a lot but I can't find any proper information or I can not fully understand because I am weak in English too.</p>
  
  <p>links:
  <a href="https://www.androidhive.info/2016/01/android-working-with-recycler-view/" rel="nofollow noreferrer">https://www.androidhive.info/2016/01/android-working-with-recycler-view/</a></p>