res/anim/fade_in.xml

<alpha xmlns:android="http://schemas.android.com/apk/res/android"
       android:interpolator="@android:anim/accelerate_interpolator"
       android:fromAlpha="0.0" 
       android:toAlpha="1.0" 
       android:duration="5000" 
       android:startOffset="5000"
       android:fillAfter="true"/>