This document discusses maintaining a consistent code style when working with a team. It recommends defining code style guidelines that establish shared coding conventions. These guidelines help new team members get up to speed and allow code reviews to focus on important issues. The document also recommends using tools like Android Studio code style settings, EditorConfig, ktlint, and detekt to automate style checking and unify styles across IDEs. Static code analysis is advocated for catching issues without running tests. Finally, the document suggests automating analysis in the CI workflow.

1. Clean Code Style
Paweł Gajda
Android Developer @ EL Passion

2. Agenda
What is Code Style?
Code Style Guidelines (for + )
IDE Code Style settings
Static Code Analysis
Kotlin static code analyzers
Extending CI workflow

3. What is Code Style?
The way I (you) create source code and
how it looks.
Everyone has his own preferred style.
It can evolve as we learn.

4. Where the problems lie?

5. Where the problems lie?
Development Team

6. Code Styles in Dev Team
CodeStyle #1
CodeStyle #2
CodeStyle #3
CodeStyle #4
I use
semicolons
in Kotlin
Shame
on you!
Never use
wildcard
imports!
⌥⌘L
again…

7. „Don’t need your code style”
⌥⌘L

8. „Don’t need your code style”
⌥⌘L

9. „Don’t need your code style”
⌥⌘L

10. „Don’t need your code style”
⌥⌘L

11. „Don’t need your code style”
⌥⌘L

12. How to write code
in the Team?

13. How to write code
in the Team?
With Code Style Guidelines

14. Code Style Guidelines

15. Code Style Guidelines
A set of rules defined as consistent coding
conventions in the team or project to:
keep codebase clean
provide faster on-boarding for new team
members
enhance code review to focus only on
important things (requires automation)

16. Code Style Guidelines for
Android Developers
Kotlin Coding Conventions
(from JetBrains)
https://kotlinlang.org/docs/reference/coding-conventions.html
Android Kotlin Style Guide
(from Google)
https://android.github.io/kotlin-guides/style.html

17. Android Studio Code Style
settings
Apply Kotlin Style Guide (from JetBrains)
Editor > Code Style > Kotlin

18. from

19. Android Studio Code Style
settings
Editor > Code Style > Kotlin > Imports
(from Google)

20. Android Studio Code Style
settings
Let’s open
Android Studio

21. How to share
Code Style Settings with GIT?
IntelliJ IDEA | Preferences | Editor | Code Style
.gitignore
/.idea!/*
!/.idea/codeStyles

22. Maintaining Code Style
between different IDEs
EditorConfig
https://editorconfig.org/
overrides IDE settings
single .editorconfig file:
[*]
indent_style = space
indent_size = 4
end_of_line = lf
insert_final_newline = true
charset = utf-8

23. Maintaining Code Style
between different IDEs
EditorConfig
https://editorconfig.org/
overrides IDE settings
single .editorconfig file:
[*]
indent_style = space
indent_size = 4
end_of_line = lf
insert_final_newline = true
charset = utf-8
matches
every file

24. Maintaining Code Style
between different IDEs
EditorConfig
https://editorconfig.org/
overrides IDE settings
single .editorconfig file:
[*]
indent_style = space
end_of_line = lf
insert_final_newline = true
charset = utf-8
[*.{kt,kts}]
indent_size = 4
matches
kotlin files

25. Maintaining Code Style
between different IDEs
EditorConfig
https://editorconfig.org/
overrides IDE settings
single .editorconfig file:
[*]
indent_style = space
indent_size = 4
end_of_line = lf
insert_final_newline = true
charset = utf-8
Let’s open
Android Studio

26. Static code analysis
analysis of code without having to
execute the app
(e.g. android lint)
stays in contrast to dynamic code
analysis
(e.g. unit tests, android tests)

27. Kotlin static code
analyzers
Android Lint
https://d.android.com/studio/write/lint
ktlint
https://ktlint.github.io/
detekt
https://arturbosch.github.io/detekt/

28. Android Lint
introduced in 2011
checks Kotlin code since 2017
focuses on Android specific issues
since Android Gradle Plugin 3.1 targets also plain Java and
Kotlin modules
./gradlew lint
./gradlew lintFix
Runs lint on all variants and applies any safe suggestions to the source code.

29. Android Lint
configuring lint options:
android {
lintOptions {
disable ’GradleDependency’
abortOnError false
ignoreWarnings true
}
}

30. ktlint
simple (no configuration)
tries to reflect JetBrains and Google Style Guides
built-in formatter
./gradlew ktlint
./gradlew ktlintFormat

31. detekt
code smells analysis
highly configurable rule sets
provides wrapper over ktlint
(formatting rule set)
IntelliJ plugin
./gradlew detekt

32. Extending CI workflow
1. Run static code analysis
2. Run unit tests
3. Run android tests
Build step duration
in one project:
15 ms
2 min
6 min

33. Conclusion
delegate code style maintenance to IDE
and static code analysers
select the tool that best suits your team’s
preferences
automate it as much as possible

34. Q&A
@pawegio