Dependency Injection Koin Vs. Dagger

Dependency Injection is mainly used for the control and management of dependencies. Koin is a simple and powerful dependencies injection library. It’s written with Kotlin. This topic will cover what Koin is, compare with Dagger and how to use it. In order to properly compare the two implementation options, firstly will focus on a project that Implemented first with Dagger and now with Koin.

Transcript

1. Dependency Injection Koin Vs. Dagger
2. SA WAD DEE KA Su Myat WTM ambassador Android Team Leader at Wave Money @devsumyat
3. What’s dependency injection? .
4. What’s a dependency…
5. What’s a dependency… A B A uses some methods of B A deepens on B
6. Dependency injection in… A B A B
7. How DI work…
8. No Injection
9. No Injection class A { val b = B() fun doSomething() { b.info } }
10. Now Injection class A(val b: B) { fun doSomething() { b.info } }
11. Now Injection class A(val b: B) { fun doSomething() { b.info } }
12. Types of Dependency Injection : Constructor class A(val b: B) { fun doSomething() { b.info } }
13. Types of Dependency Injection : Constructor class A(val b: B) { fun doSomething() { b.info } }
14. Types of Dependency Injection : Setter class A { fun doSomething(b: B) { b.info } }
15. Types of Dependency Injection : Setter class A { fun doSomething(b: B) { b.info } }
16. Types of Dependency Injection : Field class A { @Inject val b: B fun doSomething() { b.info } }
17. Types of Dependency Injection : Field class A { @Inject val b: B fun doSomething() { b.info } }
18. - More reusable - More readable - More extendable - Easy replace - Easy switching - Testable Advantage?
19. It will make you a happier developer…
20. DI options for Android
21. Let’s hands on dirty .
22. -Simple annotation structure -Readable generated code -No reflection -No runtime error -Proguard Friendly -Pure Java Dagger2
23. - 100% Kotlin - DSL very intuitive - No code generation - No reflection - No compile time overhead Koin
24. Let’s compare their steps .
25. Dagger : Dependencies & View Model implementation 'com.google.dagger:dagger:2.11' implementation 'com.google.dagger:dagger-android-support:2.11' kapt 'com.google.dagger:dagger-compiler:2.11' kapt ‘com.google.dagger:dagger-android-processor:2.11’ class NewsViewModel @Inject constructor(private val news: News) : ViewModel() { fun getNews(): String { return news.fetchNews() } }
26. @Singleton class ViewModelFactory @Inject constructor( private val creators: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<ViewModel>> ) : ViewModelProvider.Factory { override fun <T : ViewModel> create(modelClass: Class<T>): T { val creator = creators[modelClass] ?: creators.entries.firstOrNull { modelClass.isAssignableFrom(it.key) }?.value ?: throw IllegalArgumentException("unknown model class $modelClass") try { @Suppress("UNCHECKED_CAST") return creator.get() as T } catch (e: Exception) { throw RuntimeException(e) } } } Dagger : View Model Factory
27. @Target( AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY_GETTER, AnnotationTarget.PROPERTY_SETTER ) @Retention(AnnotationRetention.RUNTIME) @MapKey annotation class ViewModelKey(val value: KClass<out ViewModel>) Dagger : An Annotation Class
28. @Module abstract class ViewModelModule { @Binds @IntoMap @ViewModelKey(BrowseNewsViewModel::class) abstract fun bindNewViewModel(newsViewModel: NewsViewModel): ViewModel @Binds abstract fun bindViewModelFactory(factory: ViewModelFactory): ViewModelProvider.Factory } Dagger : View Model Module
29. @Module open class ApplicationModule { @Provides @PerApplication fun provideNews() = News } @Module abstract class ActivityModule { @ContributesAndroidInjector abstract fun mainActivityInjector(): MainActivity } Dagger : Application Module and Activity Module
30. @Singleton @Component( modules = [ AndroidInjectionModule::class, AndroidSupportInjectionModule::class, ApplicationModule::class, ActivityModule::class, ViewModelModule::class ] ) internal interface ApplicationComponent : AndroidInjector<SampleApplication> { @Component.Builder abstract class Builder : AndroidInjector.Builder<SampleApplication>() } Dagger : Application Component
31. class SampleApplication : DaggerApplication() { override fun applicationInjector(): AndroidInjector<out DaggerApplication> = DaggerApplicationComponent.builder().create(this) } Dagger : Inject into Application
32. class MainActivity : DaggerAppCompatActivity() { @Inject lateinit var viewModelFactory: ViewModelProvider.Factory private val viewmodel by lazy { ViewModelProviders.of( this, viewModelFactory )[NewsViewModel::class.java] } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) txt_new.text = viewmodel.getNews() } } Dagger : Inject into Application
33. What’s about koin? .
34. Koin : Dependencies & View Model implementation 'org.koin:koin-android:2.0.1' implementation 'org.koin:koin-androidx-scope:2.0.1' implementation 'org.koin:koin-androidx-viewmodel:2.0.1' class NewsViewModel(private val news: News) : ViewModel() { fun sendMessage() :String{ return news.fetchNews() } }
35. class App : Application() { override fun onCreate() { super.onCreate() startKoin { androidContext(this@App) modules(module) } } companion object { private val module = module { single { GetNews(get()) } viewModel { BrowseNewsViewModel(get()) } } } } Koin : Application
36. class BrowseActivity: AppCompatActivity() { val browseNewsViewModel: BrowseNewsViewModel by viewModel() override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_browse) browseNewsViewModel.fetchNews() } } Koin : Class
37. Takeaways .
38. #1 #2 #3 Let’s take some steps back and learn about Inversion of Control - the concept behind DI More exploring the fifth principle of S.O.L.I.D Hope that it makes you wanted to try Koin Takeaways
39. Thank you @devsumyat