exoplayer how to put loader while video is still loading android java code example

Example: exoplayer how to put loader while video is still loading android java

<com.google.android.exoplayer2.ui.PlayerView
        android:id="@+id/player_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:show_buffering="always"/>