fade in/out using object animator

stroke_appear_animator.xml

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android" android:ordering="sequentially">
    <objectAnimator android:propertyName="alpha"
        android:duration="200"
        android:valueFrom="1.0"
        android:valueTo="0.0"
        android:valueType="floatType" />
    <objectAnimator android:propertyName="alpha"
        android:duration="200"
        android:valueFrom="0.0"
        android:valueTo="1.0"
        android:valueType="floatType" />

</set>