1. Clean architecture: Android
Michał Szczepanik

2. WroDroid

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I have a Dream...

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What a Terrible Failure!

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What is Architecture?

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Architecture is About Intent, not Frameworks
„

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Our goal(s)
● Architecture focused on use cases and main
system function
● Clear use cases first!
● Easy to maintain
● Fast to test
● Easy to test
● Very cohesive
● Decoupled

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Step 0 (setup?)

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Architect role

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Team Role

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Android best practices ?

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Entities
The business objects of the application

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Use Cases
Use Cases orchestrate the flow of data to and
from the entities.
They are also called Interactors.

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Interface Adapters
This set of adapters convert data from the format
most convenient for the use cases and entities.
Presenters and Controllers belong here.

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Frameworks and Drivers
This is where all the details go: UI, tools,
frameworks, etc.

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How to be clean ?

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App architecture – android view

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App architecture – developer view
Presentation
Layer
Domain/Business
Layer
Data
Layer
Entities Layer
Interactors
Boundaries

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Domain (Business) Layer
● Application business rules
● All use cases (interactors)
● Android independent

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Domain (Business) Layer
Domain/Business
Layer
Entities Layer
InteractorsInterfaces
Repository(Dataaccess)Interface
● Interactors Implementation
● Use entities objects
● Most tests are here
● (JUnit plus mockito)

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Entities Layer
● Basic (minimal) business object
● Object's structure
● Low-level rules
● General truths
● Android independent
● Framework independent

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Entities Layer
● Basic java object
● No frameworks
● Test for business objects
● No mocks and stubs
Domain/Business
Layer
Entities Layer
Interactors
Boundaries

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Presentation Layer
● Logic related to UI (view and animation)
● Logic related to Activity and application lifecycle
● Fragments and Activities are only views!
● Design: MVP/MVC/MVVM pattern
● Strongly connected with Android SDK

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Presentation Layer
● Frameworks
● Integration (platform) tests
● UI tests
● (Android Instrumentation)
● (Robotium/Espresso)
● (Robolectric)
Presentation
Layer
Interactors

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Data Layer
● Deliver data needed by app
● Cache
● Service
● Design: with Repository Pattern

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Data Layer
● Repository Pattern
● Integration tests
● Unit tests
● (JUnit plus mockito)
● (Robolectric)
Implementation
RepositoryInterface
Memory
(cache)
Disk
(DB/File)
Cloud

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Testing
● Low-level tests are fast
● High-level tests are slow
● UI testing sucks ?
● Self testing code ?
● new bug = new test

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QA Team

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Monkey
adb shell monkey [options] <event-count>
-s <seed>
-v <verbosity level>

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Android Tips

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65K
Unable to execute dex: method ID not in [0, 0xffff]: 65536
Conversion to Dalvik format failed: Unable to execute dex: method ID
not in [0, 0xffff]: 65536

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How to solve it
● Find reason
– dex-method-counts
● jarjar
● Shrinking libs via Proguard
● Multidex

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Dalvik / ART
● Dalvik:
– Register-based machine
– Just in time (JIT): 2.3+
● ART
– Ahead-of-time (AOT)

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Tools?

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Lint
● Static Code Analysis
● Layouts tips and optimization
● Missing translations
● Layout performance problems
● Unused resources
● Inconsistent array sizes
● Accessibility and internationalization problems
● Icon problems
● Usability problems
● Manifest errors

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Dependency Injections
● Dagger
● RoboGuice

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Injections
● ButterKnife
● AndroidAnnotations

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Injections
class ExampleActivity extends Activity {
@InjectView(R.id.title) TextView title;
@InjectView(R.id.subtitle) TextView subtitle;
@InjectView(R.id.footer) TextView footer;
@Override public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.simple_activity);
ButterKnife.inject(this);
// TODO Use "injected" views...
}
}

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Proguard / Dexguard
● Shrinking
● Optimize
● Obfuscate

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Developer options

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Clean Architecture
● Easy to maintain
● Easy to test
● Very cohesive
● Decoupled

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WroDroid
http://www.meetup.com/WroDroid/
Clean Architecture by Unkle Bob
http://goo.gl/Z4zMHG
Architecting Android…The clean way
http://goo.gl/MF13E1
Effective Android UI
http://goo.gl/1dZxfb

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Thank you for your attention

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Questions ?
michal.szczepanik@blstream.com