Dagger2 + Kotlin: lateinit property has not been initialized

Question

I'm trying to inject the ViewModelFactory into my Activity, but it keeps throwing this same error: lateinit property viewModelFactory has not been initialized. I can't find what I may be doing wrong. See the code above from my classes

AppComponent.kt

@Component(modules = [(AppModule::class), (NetworkModule::class), (MainModule::class)]) interface AppComponent {      fun inject(application: TweetSentimentsApplication)      fun inject(mainActivity: MainActivity)      fun context(): Context      fun retrofit(): Retrofit } 

MainModule.kt

@Module class MainModule {      @Provides     fun mainViewModelFactorty(repository: TweetRepository): MainViewModelFactory = MainViewModelFactory(repository)      @Provides     fun local(database: AppDatabase): TweetLocal = TweetLocal(database)      @Provides     fun remote(tweetService: TweetService): TweetRemote = TweetRemote(tweetService)      @Provides     fun tweetService(retrofit: Retrofit): TweetService = retrofit.create(TweetService::class.java)      @Provides     fun repository(local: TweetLocal, remote: TweetRemote): TweetRepository = TweetRepository(local, remote)  } 

MainActivity.kt

class MainActivity : AppCompatActivity() {      @Inject lateinit var viewModelFactory: MainViewModelFactory      private val viewModel: MainViewModel? = null      override fun onCreate(savedInstanceState: Bundle?) {         super.onCreate(savedInstanceState)         setContentView(R.layout.main_activity)          ViewModelProviders.of(this, viewModelFactory).get(MainViewModel::class.java)          viewModel?.init("guuilp")         viewModel?.getTweetList()?.observe(this, Observer {             Toast.makeText(this, it?.size.toString(), Toast.LENGTH_LONG).show()         })     } } 

TweetSentimentsApplication.kt

open class TweetSentimentsApplication: Application(){      companion object {         lateinit var appComponent: AppComponent     }      override fun onCreate() {         super.onCreate()          initDI()     }      private fun initDI() {         appComponent = DaggerAppComponent.builder()                 .appModule(AppModule(this))                 .build()     } } 

Answer 1

You have to call the inject(mainActivity: MainActivity) method you've defined in AppComponent when you're initializing your MainActivity, that's how Dagger actually injects the dependencies you need.

override fun onCreate(savedInstanceState: Bundle?) {     super.onCreate(savedInstanceState)     setContentView(R.layout.main_activity)      // This is where the dependencies are injected     TweetSentimentsApplication.appComponent.inject(this)      ViewModelProviders.of(this, viewModelFactory).get(MainViewModel::class.java)      ... } 

Answer 2

Also, make sure that your application name is added in the AndroidManifest.xml file.

<application     android:name=".YourAppName"     ..../>