public class AndroidsCastleActivity extends Activity {

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

        class MyView extends View {

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

                @Override
                protected void onDraw(Canvas canvas) {
                        Paint paint = new Paint();
                        
                        paint.setStrokeWidth(2);//太さを2に
                        
                        paint.setColor(Color.argb(255, 255, 0, 0));//赤セット
                        canvas.drawRect(0, 0, 100, 100, paint);//四角形描画
                        
                        paint.setStyle(Paint.Style.STROKE);//中を塗りつぶさない設定に

                        paint.setAntiAlias(true);//アンチエイリアス有効に
                        paint.setColor(Color.argb(255, 255, 255, 0));//黄色セット
                        canvas.drawRoundRect(new RectF(100, 100, 200, 200), 20, 20, paint);//端円い四角形描画
                }

        }
}