samples/flickr/res/anim/fade_in.xml

<?xml version="1.0" encoding="utf-8"?>
<alpha xmlns:android="http://schemas.android.com/apk/res/android"
	android:interpolator="@android:anim/linear_interpolator"
	android:fromAlpha="0.0"
	android:toAlpha="1.0"
	android:duration="150"
/>