使いやすいシンプルな円を描くView ref: http://qiita.com/ueno-yuhei/items/c96bb7ac67aaaddcb261

file0.java

public class CircleView extends View {
    private Paint paint;

    public CircleView(Context context, AttributeSet attrs) {
        super(context, attrs);
        paint = new Paint();
    }

    public CircleView(Context context) {
        super(context);
        paint = new Paint();
    }

    public void setColor(int color){
        paint.setColor(getResources().getColor(color));
        invalidate();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        paint.setAntiAlias(true);
        canvas.drawCircle(canvas.getHeight() / 2, canvas.getHeight() / 2, (canvas.getWidth() / 2) - 2, paint);
    }
}

file1.java

circleView.setColor(R.color.white);

file2.xml

<test.ui.widget.CircleView
  android:id="@+id/circle_view"
  android:layout_width="48dp"
  android:layout_height="48dp" />

file3.java

CircleView circleView = (CircleView) view.findViewById(R.id.circle_view);
circleView.setColor(R.color.black);