Annotations Principle

※W

Annotation is a new feature introduced from Java5, used to associate any information or metadata with program elements (classes, methods, member variables, and so on).

Associated jar package: java.lang.annotation

※U

1. Generate documents. Likes @param @retrun;
2. Track code dependencies to implement alternative configuration file functions;
3. Format check at compile time. Likes @Override @Deprecated @SuppressWarnings.

※P

The explanation of principle comes from 注解Annotation实现原理与自定义注解例子.