2. [Mandatory] Abstract methods (including methods in interface) should be commented by Javadoc. Javadoc should include method instruction, description of parameters, return values and possible exceptions.

3. [Mandatory] Every class should include information of author(s) and date.

4. [Mandatory] Single line comments in a method should be put above the code to be commented, by using and multiple lines by using /* */. Alignment for comments should be noticed carefully.

6. [Recommended] Local language can be used in comments if English cannot describe the problem properly. Keywords and proper nouns should be kept in English.

7. [Recommended] When code logic changes, comments need to be updated at the same time, especially for the changes of parameters, return value, exception and core logic.

8. [For Reference] Notes need to be added when commenting out code.

9. [For Reference] Requirements for comments:
  1) Be able to represent design ideas and code logic accurately.
  2) Be able to represent business logic and help other programmers understand quickly. A large section of code without any comment is a disaster for readers. Comments are written for both oneself and other people. Design ideas can be quickly recalled even after a long time. Work can be quickly taken over by other people when needed.

10. [For Reference] Proper naming and clear code structure are self-explanatory. Too many comments need to be avoided because it may cause too much work on updating if code logic changes.