public static void main(String[] args) {
		List<Shape> shapeList = Arrays.asList(new Circle(), new Square(),
				new Triangle());
		for (Shape shape : shapeList)
			shape.draw();

		// Rhomboid 转型测试
		Rhomboid rhomboid = new Rhomboid();
		if (rhomboid instanceof Shape) {
			Shape shape = rhomboid;
			shape.draw();

			if (shape instanceof Circle) {
				Circle circle = (Circle) shape;
				circle.draw();
			}
		}
	}