CODEWITHSUNDEEP
javaandroiddagger-2
g71132
g71132

Reputation: 691

Dagger 2 cannot be provided without an constructor

Sorry for my english, now i begin learn dagger2 and i cant understand why i have error:

Error:(9, 10) error: test.dagger.dagger.modules.MainActivityPresenterModule cannot be provided without an @Inject constructor or from an @Provides- or @Produces-annotated method. test.dagger.dagger.modules.MainActivityPresenterModule is injected at test.dagger.view.activitys.MainActivity.mainActivityPresenterModule test.dagger.view.activitys.MainActivity is injected at test.dagger.dagger.components.AppComponent.injectMainActivity(mainActivity)

App

public class App extends Application {

    private static AppComponent component;

    @Override
    public void onCreate() {
        super.onCreate();
        component = DaggerAppComponent.create();
    }

    public static AppComponent getComponent() {
        return component;
    }

}

AppComponent

@Component(modules = {MainActivityPresenterModule.class})
public interface AppComponent {
    void injectMainActivity(MainActivity mainActivity);
}

MainActivityPresenterModule

@Module
public class MainActivityPresenterModule {

    @Provides
    MainActivityPresenter provideActivityPresenter(NetworkUtils networkUtils) {
        return new MainActivityPresenter(networkUtils);
    }

    @Provides
    NetworkUtils provideNetworkUtils(){
        return new NetworkUtils();
    }


}

NetworkUtils

public class NetworkUtils {

    public boolean isConnection() {
        return true;
    }

}

MainActivityPresenter

public class MainActivityPresenter {

    NetworkUtils networkUtils;

    public MainActivityPresenter(NetworkUtils networkUtils) {
        this.networkUtils = networkUtils;
    }

    public void getUser(){
        if(networkUtils.isConnection()) {
            Log.e("getUser", "getUser");
        } else {
            Log.e("no internet", "no internet connection");
        }
    }

}

MainActivity

public class MainActivity extends AppCompatActivity {


    @Inject
    MainActivityPresenterModule mainActivityPresenterModule;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        App.getComponent().injectMainActivity(MainActivity.this);


    }
}

Upvotes: 0

Views: 271

Answers (1)

NeverwinterMoon
NeverwinterMoon

Reputation: 2451

You can inject only the things that are provided in the classes annotated with @Module (only methods inside that module which are annotated with @Provides). So, you can do @Inject MainActivityPresenter presenter, for instance, not try to inject the whole module, like you tried to do. Modules should be registered on Dagger initialisation, like this (in App#onCreate)

component = DaggerAppComponent.builder()
    .mainActivityPresenterModule(MainActivityPresenterModule())
    .build()

In MainActivity you only need to call inject to be able to inject your @Inject MainActivityPresenter presenter or any other injects defined in the module, like so:

@Inject MainActivityPresenter presenter    

override fun onCreate(savedInstanceState: Bundle) {
   super.onCreate(savedInstanceState)
   (application as App).component.inject(this)

   // after #inject(this) above you can start using your injections:

   presenter.getUser()
}

Sorry, I wrote code snippets in Kotlin as it was much less to write that way, hopefully you get the idea how it looks in Java.

Upvotes: 2

Related Questions