创建完整大小应用程序的组织包、界面和类结构，即使这些文件的作用只是声明最初实现的类名称和接口。

Create the full-size application's organizational package, interface, and class structure, even if the files do nothing more than declare the class name and the interface it implements initially.

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在编程时，可以将一些接口和类声明为final，这样就不能用它们产生子类。

In programming, you can declare some interfaces and classes final so that they are not subclassed.

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使用引入(Introduction)，Aspect可以向类中添加新的方法和变量、声明一个类实现一个接口或将检查异常转换为未检查异常(unchecked exception)。

Using introduction, aspects can add new methods and variables to a class, declare that a class implements an interface, or convert checked to unchecked exceptions.

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