layout.xml

 <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/black">

        <androidx.camera.view.PreviewView
            android:id="@+id/viewFinder"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/black"
            android:foreground="@color/black"
            app:layout_constraintBottom_toTopOf="parent"
            app:layout_constraintTop_toBottomOf="parent" />
   </androidx.constraintlayout.widget.ConstraintLayout>