Android Dagger2 2.11无范围的Appcomponent参考范围绑定

Question

I use dagger2 demo by https://medium.com/@iammert/new-android-injector-with-dagger-2-part-1-8baa60152abe . I have added SharedPreferences to my AppModule.java

@Module(subcomponents = {
    MainActivityComponent.class,
    DetailActivityComponent.class,
    Detail2ActivityComponent.class})
public class AppModule {

@Provides
@Singleton
Context provideContext(Application application) {
    return application;
    }

@Provides
@Singleton //if i remove dagger works right
SharedPreferences providesSharedPreferences(Application application) {
    return PreferenceManager.getDefaultSharedPreferences(application);
    }

}

I inject SharedPreferences in MainActivity. After rebuild project i get error

If i remove annotation @Singleton by providesSharedPreferences, project rebuild right. Why is problem @Singleton annotation by providesSharedPreferences ?

Answer 1

You need to add @Singleton to the AppComponent class:

    @Singleton // <---- Add this line
    @Component(modules = {
        AndroidInjectionModule.class,
        AppModule.class,
        ActivityBuilder.class})
    public interface AppComponent {

        @Component.Builder
        interface Builder {
          @BindsInstance Builder application(Application application);
          AppComponent build();
        }

        void inject(AndroidSampleApp app);
    }