Nice implementation for material design circular progress bar (from rahatarmanahmed/CircularProgressView),
<com.github.rahatarmanahmed.cpv.CircularProgressView
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/progress_view"
android:layout_width="40dp"
android:layout_height="40dp"
app:cpv_indeterminate="true"/>