If DrawV is an Android View (or extends View), you can include it in a regular xml layout file, and then use that layout file with setContentView(int).
To reference the DrawV class in your layout, you'll need to use the fully-qualified name (with the package).
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:id="@+id/buttons"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="@+id/button_one"
android:text="One"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1.0" />
<Button
android:id="@+id/button_two"
android:text="Two"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1.0" />
</LinearLayout>
<com.example.views.DrawV
android:layout_below="@id/buttons"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
Above, the RelativeLayout is your root view. The LinearLayout, buttons, is a ViewGroup just to hold the two buttons and keep them of equal width (note the layout_width=0dp and equal layout_weight). Your DrawV view will be laid out below the buttons View, and then will match the parent container's width and height (fill it).
If you save this under src/main/res/layout/activity_circles.xml, you'll be able to use setContentView(R.layout.activity_circles) in your Activity to set the layout.