The document discusses SOLID principles and architecture patterns in Android development. It describes the five SOLID principles - single responsibility, open/closed, Liskov substitution, interface segregation, and dependency inversion. It then explains popular architecture patterns like MVC, MVP, and MVVM and compares their advantages and disadvantages. The goal of SOLID and these patterns is to make code more reusable, maintainable, flexible and suitable for team development.

1. SOLID Principles
&
Architecture in Android

2. Problem

3. SOLID Design Pattern
! Reduces tight coupling between classes.
! Loose coupled classes minimise change in code.
! Helps in making code more reusable, maintainable,
flexible, stable and suitable to work in a team.
! SOLID represents 5 design principles.

4. SOLID- 5 Design Principles
! S - Single Reasonability Principle
! O - Open - Closed Principle
! L - Liskov Substitution Principle
! I - Interface Segregation Principle
! D - Dependency Inversion Principle

5. Single Reasonability Principle (SRP)
It says that there should be not more than one reason for a class
to change and has only one responsibility.

6. Open - Closed Principle (OCP)
• Open - Software entities should be open for extension.
• Closed - Closed for modification.

8. Liskov Substitution Principle (LSP)
It states that Derived or child classes must be substitutable for
their base or parent classes.

9. Interface Segregation Principle (ISP)
• It state that do not force any client to implement an interface
which is irrelevant to them.
• Avoid Interface Pollution.

10. Dependency Inversion Principle (DIP)
• Talks about Coupling between two modules.
• High-Level Modules shouldn’t depend on low level modules.
Both should depend on abstraction.
• It focuses on the approach where the higher classes are not
dependent on the lower classes instead depend upon the
abstraction of the lower classes.

12. Architecture Pattern
! Software Architecture pattern promotes organised
programming.
! Separates application functionality which is easy to test
and provide low cost maintenance.
! MVC, MVP, MVVM are some popular design pattern.

13. MVC (Model View Controller)
Controller
(Activity/Fragment)
View
(Rendering UI)
Model
(Data State + Business
Logic)
Trigger request
Process
the
request
Update
response
N
otifies
Sometimes interact with View

14. Advantage
! It keep business logic separate in the model.
! Support asynchronous techniques
! Modification does not affect the entire model
! Faster development process
Problem
! Due to large code controller is unmanageable.
! Hinders the Unit testing
! Increased Complexity

15. MVP (Model View Presenter)
Presenter
(Intermediate)
View
(XML/Activity/Fragment)
Model
(Data State + Business
Logic)
Inform
user action
Process
the
request
Update
response
Save
&
N
otifies

16. Advantage
! Code is more readable and maintainable
! Easy testing as business logic separated from UI
! Reusable of View and Presenter
Problem
! Tight coupling between View and Presenter
! Huge amount of interfaces for interaction between layers.
! Code size is quite excessive.

17. MVVM
(Model View ViewModel)
ViewModel
(Intermediate/
RxJava/ LiveData)
View
(XML)
Repository
Local
(DataSource)
Remote
(DataSource)
Model
UI Event Observe
Response
Observe model, change callbacks
Send request
Send response
Receives
data
Receivesdata
Send
response

18. Advantage
! No tight coupling between view and view model
! No interfaces between view and model.
! Easy to unit testing and code is event driven.
Problem
! You have to create observables for each UI component.

19. More Cents
https://blog.mindorks.com/user/profile/id/17193
https://github.com/vandanasri

20. Tha󰇳󰈬 󰈘󰈢󰇼!
@ask_vandana
https://www.linkedin.com/in/androidexpertvandana