android- multiple alpha set in xml can't work

I was trying to make an alpha animation like this:

<alpha
    android:duration="300"
    android:fromAlpha="0.0"
    android:toAlpha="0.9"/>
<alpha
    android:duration="300"
    android:fromAlpha="0.9"
    android:startOffset="300"
    android:toAlpha="0.6" />
<alpha
    android:duration="300"
    android:fromAlpha="0.6"
    android:startOffset="600"
    android:toAlpha="0.9" />
<alpha
    android:duration="300"
    android:fromAlpha="0.9"
    android:startOffset="900"
    android:toAlpha="1"
    android:fillAfter="true"/>

But my Imageview is not opaque even I set toAlpha = 1 in the end.
Is that because I can only set once in xml?

This worked for me:

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
    android:fillEnabled="true"
    android:fillAfter="true">

  <alpha
    android:duration="300"
    android:fromAlpha="0.0"
    android:toAlpha="0.9" />
  <alpha
    android:duration="300"
    android:fromAlpha="0.9"
    android:startOffset="300"
    android:toAlpha="0.6" />
  <alpha
    android:duration="300"
    android:fromAlpha="0.6"
    android:startOffset="600"
    android:toAlpha="0.9" />
  <alpha
    android:duration="300"
    android:fromAlpha="0.9"
    android:startOffset="900"
    android:toAlpha="2.0" />
</set>

Try this

Animation animation = new AlphaAnimation(1,0f, 0.0f); 
animation.setDuration(1000); 
<id>.startAnimation(animation);