0. Learn more new things and actually do more new things, this is an important manifestation of ability
1. Use of beans
2. Don't be bound by rules. Try to understand, then internalize
3. Changing some concepts and habits can save time and improve personal level
4. Less error prone (compiler , runtime , double check )
5. Easier to understand
6. Let the code express your intent, not the implementation . Meaningful naming
7. A piece of code tries to describe things at one level
8. switch supports enum type
9. When assigning a value to a class, you can abstract this operation into a method and write it under the class, which is convenient for unit debugging and clear business logic