Java : Retention Policy Options #

RetentionPolicy.SOURCE #

Annotations are removed after compilation.

✅ Available only during compilation.
❌ Not present in the .class file.
❌ Not available at runtime.

Use Case: Lombok (@Getter, @Setter)

RetentionPolicy.CLASS #

Annotations are kept in the .class file but removed at runtime.

✅ Available during compilation.
✅ Exists in the compiled .class file.
❌ Not available at runtime.

Use Case: Useful when doing byte code-level post-processing

RetentionPolicy.RUNTIME #

Annotations are available even after compilation and class loading.

✅ Exists in the .class file.
✅ Available at runtime via reflection.

Use Case: Spring (@Service, @Autowired), Hibernate (@Entity, @Table).

Happy Coding 🙌