error: [Dagger/DuplicateBindings] com.example.StartRouter is bound multiple times?

问题

I have a class StartRouter. I want to provide different instances of this class to each activity, and keep it alive as long as activity is alive (for that I made @ActivityScope).

Problem is that it does not do that in my code. It seems as dagger provides one instance per annotation, in my case, once for the @ActivityScope. This scope is a custom dagger scope.

Here are my two modules (One for each activity), first module:

@Module
public class SplashModule {

    @Provides
    SplashVMFactory splashVMFactory(StartRouter startRouter){
        return new SplashVMFactory(startRouter);


    @Provides
    StartRouter startRouter(){
        return new StartRouter();
    }

}

And second module:

@Module
public class QuestionModule {

    @Provides
    QuestionVMFactory questionVMFactory(StartRouter startRouter){
        return new QuestionVMFactory(startRouter);
    }

    @Provides
    StartRouter startRouter(){
        return new StartRouter();
    }

}

And I have this:

@Module
public abstract class BinderModule {

    @ActivityScope
    @ContributesAndroidInjector(modules = SplashModule.class)
    abstract SplashActivity bindSplashActivity();

    @ActivityScope
    @ContributesAndroidInjector(modules = QuestionModule.class)
    abstract QuestionActivity bindQuestionActivity();

}

And my application component:

@ApplicationScope
@Component(modules = {AndroidInjectionModule.class,
        BinderModule.class,
        SplashModule.class,
        QuestionModule.class})
public interface AppComponent {

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

    void inject(App app);

}

When I run this I get this error:

error: [Dagger/DuplicateBindings] com.example.StartRouter is bound multiple times:
@Provides com.example.StartRouter com.example.QuestionModule.startRouter()
@Provides com.example.StartRouter com.example.SplashModule.startRouter()
com.example.StartRouter is injected at
com.example.LoginModule.loginVMFactory(…, startRouter)
com.example.LoginVMFactory is injected at
com.example.LoginActivity.factory
com.example.LoginActivity is injected at
dagger.android.AndroidInjector.inject(T) [com.example.AppComponent ? com.example.BinderModule_BindLoginActivity.LoginActivitySubcomponent]
It is also requested at:
com.example.QuestionModule.questionVMFactory(…, startRouter)
The following other entry points also depend on it:
dagger.android.AndroidInjector.inject(T) [com.example.AppComponent ? com.example.BinderModule_BindQuestionActivity.QuestionActivitySubcomponent]

(Also have StartRouter provided in other modules than the two examples as you can see from my error).

I thought, if I have understood right, that from the usage of @ActivityScope in BinderModule with @ContributesAndroidInjector would create different Components for each activity that is alive as long as the activity itself, but I seem to have understood wrong?

If I differentiate between the different StartRouter in my @modules by using @named and having 1 module to provide without @named then that will solve the problem by providing different StartRouter instances? But that does not help me with my problem. My problem is, in short, I have trouble providing @ActivityScoped StartRouter instances (1 for each activity) that is alive as loong as the activity itself. Any suggestions on how I could do that?

回答1:

Your setup is fine but for the fact that you also add both modules (both binding StartRouter) to AppComponent, thus the error that you bind it multiple times.

@Component(modules = {AndroidInjectionModule.class,
        BinderModule.class,
        SplashModule.class,    // <== 1.
        QuestionModule.class}) // <== 2.
public interface AppComponent { .. }

Since you want one instance per Activity there is no need to add the modules to AppComponent. You should be able to remove those 2 modules from it.

来源：https://stackoverflow.com/questions/56761359/error-dagger-duplicatebindings-com-example-startrouter-is-bound-multiple-time

标签

android

dagger-2

dagger