The modern view on implementation of classic design patterns in Java
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The document discusses the modern implementation of classic design patterns in Java, emphasizing best practices and common pitfalls. It covers various design patterns including Singleton, Builder, and Factory Method, along with suggestions for using functional interfaces and dependency injection. The author shares personal insights and experiences regarding the usage of these patterns in contemporary Java development.
The modern view on implementation of classic design patterns in Java
- 1. The modern view on implementation of classic design patterns in Java Mikalai Alimenkou http://xpinjection.com @xpinjection
- 4. Disclaimer This is only my personal experience
- 5. Familiar with design patterns?
- 6. Holy bible for developers
- 7. Java have long/slow roadmap
- 8. You could follow code samples https://github.com/xpinjection/design-patterns
- 10. DI fight against Singleton
- 11. This is common anti- pattern now Isolate existing Singletons from new code with DI DI containers ‘killed’ Singleton pattern
- 13. #2: Builder
- 14. ‘Storing’ VS ‘runtime’ style builders Builder is the most common pattern Java is still bad in handling properties
- 16. #3: Prototype
- 17. DI container handle prototypes in their own way Clone method in Object is confusing Useful for domain model with DDD style
- 20. Use basic functional interfaces if possible Doesn’t work for abstract factory Constructor is also a function
- 22. #5: Adapter
- 23. Functional interfaces are interchangeable Doesn’t work for complex interfaces Use basic functional interfaces if possible
- 25. #6: Proxy
- 26. May be done with composite functions Inline lambda wrapping is also available Main usage with AOP and DI containers
- 27. Libs for manual proxy creation • java.lang.reflect.Proxy • Byte Buddy (http://bytebuddy.net) • cglib (https://github.com/cglib/cglib) • javassist (https://github.com/jboss- javassist/javassist)
- 30. Utilize basic functional interfaces Inline needed parts in tests and simple clients Use composition instead of inheritance
- 32. #8: Command
- 33. Collect commands in collection or combine them Doesn’t work with complex commands (with ‘undo’) Dude, this is just a plain lambda!
- 35. #9: Chain of Responsibility
- 36. Combine consumers in the chain Doesn’t work for “workflow” handlers May be use typed functions pipeline?
- 38. #10: Strategy
- 39. Inline strategy in tests and other light clients Store strategies in single holder as static methods Dude, this is just a plain lambda again!
- 41. #11: Iterator
- 42. Use Streams everywhere Create own streams with Spliterator Forget about manual iterations
- 44. #12: Decorator
- 45. Wrap function with lambda Combine functions to provide additional behavior Use the Proxy approaches
- 47. #13: Observer
- 48. Pass methods as listeners Observer and Listener are functional interfaces Inline listener logic in lambda
- 50. #14: Visitor
- 51. Use general implementation Try to use default methods where applicable Very rarely used design pattern
- 53. And remember…