title: Android animation z-index
body: <p>I'm using relative layout, and I have the following items inside of them</p>
  
  <pre><code>&lt;foo
      android:id="@+id/first_one" &gt;
  
  &lt;bar
      android:id="@+id/second_one"
      android:layout_below="@+id/first_one" &gt;
  </code></pre>
  
  <p>I want to start an animation on <code>bar</code> but it should be z-indexed behind <code>foo</code>. The thing is that in order to do that, I need to declare <code>foo</code> after <code>bar</code>. BUT I can't do that, because since <code>bar</code> is supposed to be below <code>foo</code>   it throws null pointer exception.</p>
  
  <p>any ideas?</p>