mPopWindow.setAnimationStyle(R.style.anim_pop_bottombar);

styles.xml:

 <style name="anim_pop_bottombar">
        <item name="android:windowEnterAnimation">@anim/bottom_in</item>
        <item name="android:windowExitAnimation">@anim/bottom_out</item>
    </style>
 

anim : bottom_in:

<?xml version="1.0" encoding="utf-8"?>
<translate
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="300"
    android:fromYDelta="100%p"
    android:toYDelta="0"/>

bottom_out:

<?xml version="1.0" encoding="utf-8"?>
<translate
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="300"
    android:fromYDelta="0"
    android:toYDelta="100%p"/>