Java 匕首2不工作

我正试图通过构造函数注入为我的

片段

注入一个演示者（这样我就不需要为演示者创建

@提供

方法）

我相信我做的是正确的，但我仍然收到以下错误：

如果没有@Provides-或@products注释方法，则无法提供MainFragmentPresenter

以下是我的设置：

ApplicationComponent.java

@Singleton
@Component(
        modules = {
                NetworkModule.class
        }
)
public interface ApplicationComponent {

    NetworkService networkService();
}

@PerFragment
@Component(
        dependencies = ApplicationComponent.class,
        modules = MainFragmentPresenterModule.class
)
public interface MainFragmentComponent {

    MainFragmentView view();

    void inject(MainFragment mainFragment);
}

@Module
public class MainFragmentPresenterModule {

    private final MainFragmentView _view;

    public MainFragmentPresenterModule(MainFragmentView view) {
        _view = view;
    }

    @Provides
    @PerFragment
    MainFragmentView provideMainFragmentView() {
        return _view;
    }
}

@Module
public class NetworkModule {

    @Provides
    @Singleton
    OkHttpClient provide_OkHttpClient() {
        return new OkHttpClient();
    }

    @Provides
    @Singleton
    OpenWeatherEndpoints provide_OpenWeatherAPI(OkHttpClient client) {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("http://api.openweathermap.org/data/2.5/")
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(client)
                .build();

        return retrofit.create(OpenWeatherEndpoints.class);

    }

    @Provides
    @Singleton
    YoutubeEndpoints provide_YoutubeEndpoints(OkHttpClient client) {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://www.googleapis.com/youtube/v3/")
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(client)
                .build();

        return retrofit.create(YoutubeEndpoints.class);

    }

    @Provides
    @Singleton
    NetworkService provide_NetworkService(OpenWeatherEndpoints openWeatherEndpoints, YoutubeEndpoints youtubeEndpoints) {
        return new NetworkService(openWeatherEndpoints, youtubeEndpoints);
    }
}

@Scope
@Retention(RUNTIME)
@interface PerFragment {
}

public class MainFragmentPresenterImpl implements MainFragmentPresenter {
    private final MainFragmentView _view;
    private NetworkService _service;

    @Inject MainFragmentPresenterImpl(MainFragmentView view, NetworkService networkService) {
        _view = view;
        _service = networkService;
    }
}

MainFragmentComponent.java

@Singleton
@Component(
        modules = {
                NetworkModule.class
        }
)
public interface ApplicationComponent {

    NetworkService networkService();
}

@PerFragment
@Component(
        dependencies = ApplicationComponent.class,
        modules = MainFragmentPresenterModule.class
)
public interface MainFragmentComponent {

    MainFragmentView view();

    void inject(MainFragment mainFragment);
}

@Module
public class MainFragmentPresenterModule {

    private final MainFragmentView _view;

    public MainFragmentPresenterModule(MainFragmentView view) {
        _view = view;
    }

    @Provides
    @PerFragment
    MainFragmentView provideMainFragmentView() {
        return _view;
    }
}

@Module
public class NetworkModule {

    @Provides
    @Singleton
    OkHttpClient provide_OkHttpClient() {
        return new OkHttpClient();
    }

    @Provides
    @Singleton
    OpenWeatherEndpoints provide_OpenWeatherAPI(OkHttpClient client) {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("http://api.openweathermap.org/data/2.5/")
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(client)
                .build();

        return retrofit.create(OpenWeatherEndpoints.class);

    }

    @Provides
    @Singleton
    YoutubeEndpoints provide_YoutubeEndpoints(OkHttpClient client) {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://www.googleapis.com/youtube/v3/")
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(client)
                .build();

        return retrofit.create(YoutubeEndpoints.class);

    }

    @Provides
    @Singleton
    NetworkService provide_NetworkService(OpenWeatherEndpoints openWeatherEndpoints, YoutubeEndpoints youtubeEndpoints) {
        return new NetworkService(openWeatherEndpoints, youtubeEndpoints);
    }
}

@Scope
@Retention(RUNTIME)
@interface PerFragment {
}

public class MainFragmentPresenterImpl implements MainFragmentPresenter {
    private final MainFragmentView _view;
    private NetworkService _service;

    @Inject MainFragmentPresenterImpl(MainFragmentView view, NetworkService networkService) {
        _view = view;
        _service = networkService;
    }
}

MainFragmentPresenterModule.java

@Singleton
@Component(
        modules = {
                NetworkModule.class
        }
)
public interface ApplicationComponent {

    NetworkService networkService();
}

@PerFragment
@Component(
        dependencies = ApplicationComponent.class,
        modules = MainFragmentPresenterModule.class
)
public interface MainFragmentComponent {

    MainFragmentView view();

    void inject(MainFragment mainFragment);
}

@Module
public class MainFragmentPresenterModule {

    private final MainFragmentView _view;

    public MainFragmentPresenterModule(MainFragmentView view) {
        _view = view;
    }

    @Provides
    @PerFragment
    MainFragmentView provideMainFragmentView() {
        return _view;
    }
}

@Module
public class NetworkModule {

    @Provides
    @Singleton
    OkHttpClient provide_OkHttpClient() {
        return new OkHttpClient();
    }

    @Provides
    @Singleton
    OpenWeatherEndpoints provide_OpenWeatherAPI(OkHttpClient client) {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("http://api.openweathermap.org/data/2.5/")
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(client)
                .build();

        return retrofit.create(OpenWeatherEndpoints.class);

    }

    @Provides
    @Singleton
    YoutubeEndpoints provide_YoutubeEndpoints(OkHttpClient client) {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://www.googleapis.com/youtube/v3/")
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(client)
                .build();

        return retrofit.create(YoutubeEndpoints.class);

    }

    @Provides
    @Singleton
    NetworkService provide_NetworkService(OpenWeatherEndpoints openWeatherEndpoints, YoutubeEndpoints youtubeEndpoints) {
        return new NetworkService(openWeatherEndpoints, youtubeEndpoints);
    }
}

@Scope
@Retention(RUNTIME)
@interface PerFragment {
}

public class MainFragmentPresenterImpl implements MainFragmentPresenter {
    private final MainFragmentView _view;
    private NetworkService _service;

    @Inject MainFragmentPresenterImpl(MainFragmentView view, NetworkService networkService) {
        _view = view;
        _service = networkService;
    }
}

NetworkModule.java

@Singleton
@Component(
        modules = {
                NetworkModule.class
        }
)
public interface ApplicationComponent {

    NetworkService networkService();
}

@PerFragment
@Component(
        dependencies = ApplicationComponent.class,
        modules = MainFragmentPresenterModule.class
)
public interface MainFragmentComponent {

    MainFragmentView view();

    void inject(MainFragment mainFragment);
}

@Module
public class MainFragmentPresenterModule {

    private final MainFragmentView _view;

    public MainFragmentPresenterModule(MainFragmentView view) {
        _view = view;
    }

    @Provides
    @PerFragment
    MainFragmentView provideMainFragmentView() {
        return _view;
    }
}

@Module
public class NetworkModule {

    @Provides
    @Singleton
    OkHttpClient provide_OkHttpClient() {
        return new OkHttpClient();
    }

    @Provides
    @Singleton
    OpenWeatherEndpoints provide_OpenWeatherAPI(OkHttpClient client) {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("http://api.openweathermap.org/data/2.5/")
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(client)
                .build();

        return retrofit.create(OpenWeatherEndpoints.class);

    }

    @Provides
    @Singleton
    YoutubeEndpoints provide_YoutubeEndpoints(OkHttpClient client) {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://www.googleapis.com/youtube/v3/")
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(client)
                .build();

        return retrofit.create(YoutubeEndpoints.class);

    }

    @Provides
    @Singleton
    NetworkService provide_NetworkService(OpenWeatherEndpoints openWeatherEndpoints, YoutubeEndpoints youtubeEndpoints) {
        return new NetworkService(openWeatherEndpoints, youtubeEndpoints);
    }
}

@Scope
@Retention(RUNTIME)
@interface PerFragment {
}

public class MainFragmentPresenterImpl implements MainFragmentPresenter {
    private final MainFragmentView _view;
    private NetworkService _service;

    @Inject MainFragmentPresenterImpl(MainFragmentView view, NetworkService networkService) {
        _view = view;
        _service = networkService;
    }
}

PerFragment.java

@Singleton
@Component(
        modules = {
                NetworkModule.class
        }
)
public interface ApplicationComponent {

    NetworkService networkService();
}

@PerFragment
@Component(
        dependencies = ApplicationComponent.class,
        modules = MainFragmentPresenterModule.class
)
public interface MainFragmentComponent {

    MainFragmentView view();

    void inject(MainFragment mainFragment);
}

@Module
public class MainFragmentPresenterModule {

    private final MainFragmentView _view;

    public MainFragmentPresenterModule(MainFragmentView view) {
        _view = view;
    }

    @Provides
    @PerFragment
    MainFragmentView provideMainFragmentView() {
        return _view;
    }
}

@Module
public class NetworkModule {

    @Provides
    @Singleton
    OkHttpClient provide_OkHttpClient() {
        return new OkHttpClient();
    }

    @Provides
    @Singleton
    OpenWeatherEndpoints provide_OpenWeatherAPI(OkHttpClient client) {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("http://api.openweathermap.org/data/2.5/")
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(client)
                .build();

        return retrofit.create(OpenWeatherEndpoints.class);

    }

    @Provides
    @Singleton
    YoutubeEndpoints provide_YoutubeEndpoints(OkHttpClient client) {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://www.googleapis.com/youtube/v3/")
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(client)
                .build();

        return retrofit.create(YoutubeEndpoints.class);

    }

    @Provides
    @Singleton
    NetworkService provide_NetworkService(OpenWeatherEndpoints openWeatherEndpoints, YoutubeEndpoints youtubeEndpoints) {
        return new NetworkService(openWeatherEndpoints, youtubeEndpoints);
    }
}

@Scope
@Retention(RUNTIME)
@interface PerFragment {
}

public class MainFragmentPresenterImpl implements MainFragmentPresenter {
    private final MainFragmentView _view;
    private NetworkService _service;

    @Inject MainFragmentPresenterImpl(MainFragmentView view, NetworkService networkService) {
        _view = view;
        _service = networkService;
    }
}

MainFragmentPresenterImpl.java

@Singleton
@Component(
        modules = {
                NetworkModule.class
        }
)
public interface ApplicationComponent {

    NetworkService networkService();
}

@PerFragment
@Component(
        dependencies = ApplicationComponent.class,
        modules = MainFragmentPresenterModule.class
)
public interface MainFragmentComponent {

    MainFragmentView view();

    void inject(MainFragment mainFragment);
}

@Module
public class MainFragmentPresenterModule {

    private final MainFragmentView _view;

    public MainFragmentPresenterModule(MainFragmentView view) {
        _view = view;
    }

    @Provides
    @PerFragment
    MainFragmentView provideMainFragmentView() {
        return _view;
    }
}

@Module
public class NetworkModule {

    @Provides
    @Singleton
    OkHttpClient provide_OkHttpClient() {
        return new OkHttpClient();
    }

    @Provides
    @Singleton
    OpenWeatherEndpoints provide_OpenWeatherAPI(OkHttpClient client) {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("http://api.openweathermap.org/data/2.5/")
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(client)
                .build();

        return retrofit.create(OpenWeatherEndpoints.class);

    }

    @Provides
    @Singleton
    YoutubeEndpoints provide_YoutubeEndpoints(OkHttpClient client) {

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://www.googleapis.com/youtube/v3/")
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .client(client)
                .build();

        return retrofit.create(YoutubeEndpoints.class);

    }

    @Provides
    @Singleton
    NetworkService provide_NetworkService(OpenWeatherEndpoints openWeatherEndpoints, YoutubeEndpoints youtubeEndpoints) {
        return new NetworkService(openWeatherEndpoints, youtubeEndpoints);
    }
}

@Scope
@Retention(RUNTIME)
@interface PerFragment {
}

public class MainFragmentPresenterImpl implements MainFragmentPresenter {
    private final MainFragmentView _view;
    private NetworkService _service;

    @Inject MainFragmentPresenterImpl(MainFragmentView view, NetworkService networkService) {
        _view = view;
        _service = networkService;
    }
}

当我尝试将演示者注入我的片段时

public class MainFragment extends Fragment implements MainFragmentView {

    public static final String TAG = "MainFragment";

    @Inject
    MainFragmentPresenter _presenter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        DaggerMainFragmentComponent.builder()
                .applicationComponent(WeatherForecastApp.get(getContext()).getAppComponent())
                .mainFragmentPresenterModule(new MainFragmentPresenterModule(this))
                .build()
                .inject(this);
   }
}

---

非常感谢您的帮助！谢谢。

您需要添加从MainFragmentPresenterImpl到MainFragmentPresenter的绑定。Dagger不会在类型之间强制转换，所以您需要使用方法显式地执行此操作@Binds相当于只返回其参数的@Provides方法，但它的实现效率更高。只需按以下方式更改模块：

@Module
public abstract class MainFragmentPresenterModule {
    ...
    @Binds
    abstract MainFragmentPresenter(MainFragmentPresenterImpl impl);
}

DaggerMainFragmentComponent.builder()
    .applicationComponent(WeatherForecastApp.get(getContext()).getAppComponent())
    .mainFragmentView(this)
    .build()
    .inject(this);

此外，您还可以通过使用

现在，由于您的模块没有构造函数，Dagger不需要提供实例，因此您可以这样构造组件：

@Module
public abstract class MainFragmentPresenterModule {
    ...
    @Binds
    abstract MainFragmentPresenter(MainFragmentPresenterImpl impl);
}

DaggerMainFragmentComponent.builder()
    .applicationComponent(WeatherForecastApp.get(getContext()).getAppComponent())
    .mainFragmentView(this)
    .build()
    .inject(this);