How to set android xml layout to custom view and be able to draw on it

I want to add xml layout to custom view. It is done in commented section of code. But I am not able to draw after doing that. This Code paint red circle in center of screen. After uncommenting commented lines circle is not painted.

public class Main extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(new MyView(this));
}

public class MyView extends View {

    Paint paint;

    public MyView(Context context) {
         super(context);

//      View view = inflate(context, R.layout.activity_main_zadanie, null);
//      view.setFocusable(true);
//        addView(view);

         paint = new Paint();
    }

    @Override
    protected void onDraw(Canvas canvas) {
       // TODO Auto-generated method stub
       super.onDraw(canvas);
       int x = getWidth();
       int y = getHeight();
       int radius;
       radius = 100;
       paint.setStyle(Paint.Style.FILL);
       paint.setColor(Color.WHITE);
       canvas.drawPaint(paint);
       // Use Color.parseColor to define HTML colors
       paint.setColor(Color.parseColor("#CD5C5C"));
       canvas.drawCircle(x / 2, y / 2, radius, paint);
   }
}

}