[第一节：面向对象之抽象](%E7%AC%AC%E4%B8%80%E8%8A%82%EF%BC%9A%E9%9D%A2%E5%90%91%E5%AF%B9%E8%B1%A1%E4%B9%8B%E6%8A%BD%E8%B1%A1.md) [第二节：面向对象之继承](%E7%AC%AC%E4%BA%8C%E8%8A%82%EF%BC%9A%E9%9D%A2%E5%90%91%E5%AF%B9%E8%B1%A1%E4%B9%8B%E7%BB%A7%E6%89%BF.md) [第三节：面向对象之多态](%E7%AC%AC%E4%B8%89%E8%8A%82%EF%BC%9A%E9%9D%A2%E5%90%91%E5%AF%B9%E8%B1%A1%E4%B9%8B%E5%A4%9A%E6%80%81.md) [第四节：接口](%E7%AC%AC%E5%9B%9B%E8%8A%82%EF%BC%9A%E5%80%9F%E5%8F%A3.md)