title: Animation and animator android
body: <p>I'm trying to create a fragemnt that can animate - flip/rotate.
  I found the start here : <a href="http://developer.android.com/training/animation/cardflip.html" rel="nofollow">http://developer.android.com/training/animation/cardflip.html</a>
  <br> But now I want another animation - from top to bottom but I dont understand how those <code>objectAnimator</code> work.<br>
  From how I saw the other animations worked I tried creating the top to bottom animation like this :
  up_in.xml</p>
  
  <pre><code>&lt;set xmlns:android="http://schemas.android.com/apk/res/android"&gt;
      &lt;!-- Before rotating, immediately set the alpha to 0. --&gt;
      &lt;objectAnimator
          android:valueFrom="1.0"
          android:valueTo="0.0"
          android:propertyName="alpha"
          android:duration="0" /&gt;
  
      &lt;!-- Rotate. --&gt;
      &lt;objectAnimator
          android:valueFrom="-180"
          android:valueTo="0"
          android:propertyName="rotationX"
          android:interpolator="@android:interpolator/accelerate_decelerate"
          android:duration="@integer/card_flip_time_full" /&gt;
  
      &lt;!-- Half-way through the rotation (see startOffset), set the alpha to 1. --&gt;
      &lt;objectAnimator
          android:valueFrom="0.0"
          android:valueTo="1.0"
          android:propertyName="alpha"
          android:startOffset="@integer/card_flip_time_half"
          android:duration="1" /&gt;
  &lt;/set&gt;
  </code></pre>
  
  <p>up_out.xml</p>
  
  <pre><code>&lt;set xmlns:android="http://schemas.android.com/apk/res/android"&gt;
      &lt;!-- Rotate. --&gt;
      &lt;objectAnimator
          android:valueFrom="0"
          android:valueTo="180"
          android:propertyName="rotationX"
          android:interpolator="@android:interpolator/accelerate_decelerate"
          android:duration="@integer/card_flip_time_full" /&gt;
  
      &lt;!-- Half-way through the rotation (see startOffset), set the alpha to 0. --&gt;
      &lt;objectAnimator
          android:valueFrom="1.0"
          android:valueTo="0.0"
          android:propertyName="alpha"
          android:startOffset="@integer/card_flip_time_half"
          android:duration="1" /&gt;
  &lt;/set&gt;
  </code></pre>
  
  <p>What I get from this animation is the right motion, but in the middle it suddenly dissappear for a moment.<br>
  I want to understand why this doesnt work, and in general how the objectAnimator works.</p>