java 注解为何还有元数据之称?

Question

什么是元数据?为何在java中把元数据称为注解?请诸位指教

Answer 1

https://docs.oracle.com/javas...

Lesson: Annotations

Annotations, a form of metadata, provide data about a program that is not part of the program itself. Annotations have no direct effect on the operation of the code they annotate.

Annotations have a number of uses, among them:

• Information for the compiler — Annotations can be used by the compiler to detect errors or suppress warnings.
• Compile-time and deployment-time processing — Software tools can process annotation information to generate code, XML files, and so forth.
• Runtime processing — Some annotations are available to be examined at runtime.