Android antipatterns
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The document discusses various Android anti-patterns including premature optimization, unnecessary use of reactive programming, and null pointer issues. It emphasizes better coding practices like using enums for clarity, avoiding needless complexities, and understanding when to apply reactive methods versus simpler solutions. Additional anti-patterns mentioned include superstitious coding and tester driven development, along with references for further reading.
![Anti-pattern
a common response to a recurring problem that is usually
ineffective [and] usually counter-productive.](https://image.slidesharecdn.com/androidantipatterns-161205103602/85/Android-antipatterns-2-320.jpg)
![-keep public enum
android-how-to-keep-enum-from-proguard [link]
proguard-wont-keep-a-class-members-enums [link]
Proguard config
#keep enum classes
-keep public enum com.intive.nearbyplaces.model.ApiProviderType** {
**[] $VALUES;
public *;
}
You can also keep the enums...](https://image.slidesharecdn.com/androidantipatterns-161205103602/85/Android-antipatterns-14-320.jpg)
Android antipatterns
- 2. Anti-pattern a common response to a recurring problem that is usually ineffective [and] usually counter-productive.
- 5. Donald Knuth Author of “The Art of Computer Programming” Sir Tony Hoare Quick Sort, Null-reference, Hoare logic
- 6. Donald Knuth: For those who don't work to strict memory or CPU cycle limits, PrematureOptimization is an AntiPattern, since there is only cost and no benefit. For those who do, it is often confused with poor coding, or with misguided attempts at writing optimal code. Quotes original author is still questioned. “We should forget about small efficiencies, say about 97% of the time”
- 7. LET’S REMOVE ALL ENUMS!
- 8. WHY?
- 9. Enums have obvious benefits: - make the code more self-documenting - the compiler can assign default values to enumerator automatically - prevents the programmer from writing illogical code - e.g. multiplying enums? - IDEs, type checking, correctness etc.
- 10. Change it to integers? public class View { public static final int VISIBLE = 0x00000000; public static final int INVISIBLE = 0x00000004; public static final int GONE = 0x00000008; }
- 11. https://developer.android.com/reference/android/support/annotation/IntDef.html @IntDef would be a better idea... @IntDef({NAVIGATION_MODE_STANDARD, NAVIGATION_MODE_LIST, NAVIGATION_MODE_TABS})
- 12. Which leaves us with... public class View { public static final int VISIBLE = 0x00000000; public static final int INVISIBLE = 0x00000004; public static final int GONE = 0x00000008; @IntDef({VISIBLE, INVISIBLE, GONE}) @Retention(RetentionPolicy.SOURCE) public @interface Visibility {} }
- 14. -keep public enum android-how-to-keep-enum-from-proguard [link] proguard-wont-keep-a-class-members-enums [link] Proguard config #keep enum classes -keep public enum com.intive.nearbyplaces.model.ApiProviderType** { **[] $VALUES; public *; } You can also keep the enums...
- 17. Silver-bullet
- 18. LET’S DO EVERYTHING REACTIVE
- 19. If you don’t need it - don’t use it! Library Method count Butterknife 119 Retrofit2 402 Realm 2343 com.google.android 9651 Glide 2364 Kotlin 5090 RxJava + RxBinding + RxPref + RxLoc + RxTuples 5319 + 758 + 90 + 176 + 137 = 6480 Hawk 121 RxJava is heavy on android *without proguard
- 20. Use reactive: - Constant flow of data - “Instant” search cases Debounce(), throttleFirst() - Reflecting settings in UI ? It’s NOT only RxJava Maybe Android bindings are enough?
- 21. Don’t use reactive: - button clicks @Click is probably more concise - Simple “lookups” from db Category category = Category.forId(263); - Large, expensive, cached objects
- 23. Duplication
- 24. RxJava Duplication of reactive approaches EventBus
- 25. EventBus Don’t use a separate library - both approaches are reactive!
- 26. /** * Rx-style Event bus. Each event type implements its own subscription methods. */ public class RxEventBus { private static RxEventBus instance; private PublishSubject<Location> mGpsLocationEvents = PublishSubject.create(); public static RxEventBus instanceOf() { if (instance == null) { instance = new RxEventBus(); } return instance; } /** * Pass events of LOCATION type down to event listeners. */ public void newLocationEvent(Location location) { mGpsLocationEvents.onNext(location); } /** * Subscribe to this LOCATION type Observable. On event Action will be called. */ public Observable<Location> getLocationEvents() { return mGpsLocationEvents; } }
- 28. Nullpointer hell
- 29. @NonNull Java is not null-safe
- 30. @NonNull How can we overcome this?
- 31. @NonNull - We could use a higher order language like Kotlin/Scala/Dart - Optional<Type> - Annotations @NonNull @Nullable
- 32. @NonNull funtion add(@NonNull Square s1, @NonNull Square s2) { }
- 33. @NonNull funtion add(@NonNull Square s1, @NonNull Square s2) { } TEDIOUS!
- 34. @NonNull Let’s assume parameters and return values are NonNull by default
- 35. @NonNull file: package-info.java @ParametersAreNonnullByDefault @ReturnValuesAreNonnullByDefault package com.intive.nearbyplaces; Gradle tasks for generating these files: download, download
- 36. Antipatterns summary - Premature optimization - Silver bullet - Duplication - Nullpointer hell
- 37. Other Antipatterns Superstitious coding Coding to handle error conditions which are already known to be impossible. Reinventing the square wheel/ Not Invented Here (NIH) Failing to adopt an existing solution and instead adopting a custom solution which performs much worse than the existing one Tester Driven Development Removing the determination of requirements and letting the testers (or the QA team) drive what they think the software should be through the testing (or QA) process. Lava flow Retaining undesirable (redundant or low-quality) code because removing it is too expensive
- 38. Links - Premature optimization is the root of all evil - Donald Knuth link - The antipattern catalogue Donald Knuth - link - The price of enums Android Developers - link - AntiPatterns: Refactoring Software, Architectures, and Projects in Crisis link - When not to use reactive - link - NonNull gradle task generator - link, link