Not so many developers are clearly make a distinction between design and architecture, and the experience of the interviews shows that the basic paradigm of OOP often cause difficulty. Java language is quite old and not all principles were implemented properly in it, and the abundance of frameworks further confuses developers. This presentation will discuss the basics of OOP and modern look on them, the benefits and harms of inheritance, interfaces, and the applicability of the opportunities that they offer for the ever-growing project. It will also consider the appearance of the normal cycle of code to work on TDD, how to postpone the architectural and design solutions until the right moment, tried and tested over the years architectural design patterns, principles of good code design. This talk will be useful to those who want to create high-quality, understandable and easy to support solutions in Java.

1. OOP paradigm, the basics of
good design and architecture
of Java applications
Mikalai Alimenkou
http://xpinjection.com
@xpinjection

3. Disclaimer
This is all my
personal experience

4. #1. Use interfaces everywhere
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Clear protocols
Natural TDD cycle
Delayed transport decisions
Easy logic extension
Simple scalability

5. #2. Inheritance is evil
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Current and future behavior inherited
‘Protected’ breaks encapsulation
Long inheritance chains is hell
Dependencies on frameworks inherited

6. #3. ‘Natural’ encapsulation
POJO bullshit
game

7. #4. SOLID design principles
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SRP – Single Responsibility Principle
OCP – Open/Closed Principle
LSP – Liskov Substitution Principle
ISP – Interface Segregation Principle
DIP – Dependency Inversion Principle
Don’t forget about: DRY + KISS + YAGNI

8. #5. DAO layer for data access

9. #6. All logic is in services

10. #7. Don’t rely on frameworks
Are you
crazy?

11. And remember…

12. @xpinjection
http://xpinjection.com
mikalai.alimenkou@xpinjection.com