DI on generic class where a superclasses generic type is a generated class

I’m currently building an app with Dagger 2 and Android DataBinding. I have a generic Activity base class in which the generic type specifies what ViewDataBinding subclass any child activities use for their UI.

public abstract class BaseActivity<T extends ViewDataBinding> extends AppCompatActivity {
    @Inject
    protected EventBus mEventBus;
    @Inject
    protected T mBinding;

    ...
}

public class MainActivity extends BaseActivity<ActivityMainBinding> {
    ...
}

Whenever I attempt to build my project the compilation fails and Dagger 2 gives no indication as to what the underlying issue is. After a lot of trial and error I could only find one answer; it seems as though Dagger 2 doesn’t like having a Component that injects into a generic class whose generic type is a generated class (i.e. ActivityMainBinding in the above example). If I remove the generic type from even MainActivity (i.e. make it default to using ViewDataBinding) it builds and runs as expected.

Is there any solution to this?

[fullkomnun]

I encountered this issue when using an abstract generic base class with a single type parameter that is bound to extend ViewDataBinding. When extending this base class and defining the concrete generated data binding class and trying to inject into the subclass (when the base class has any kind of injections) dagger fails to generate the MembersInjector for the base class since it cannot find the symbol for the generated data binding class. build config: dagger 2.8, android-gradle-plugin 2.2.3, gradle 3.2.1, build-tools 25.0.2. Also tried to use the latest android-gradle-plugin(2.3.0-beta2) and gradle(3.3). Tried to use android gradle plugin’s annotation processing support available since version 2.2.0 and the good old android-apt plugin.

public abstract class BindableBaseController<B extends ViewDataBinding> extends BaseController {
  @Inject void setupLeakCanary(LeakCanaryProxy leakCanaryProxy) {
    addLifecycleListener(new LeakCanaryControllerLifecycleListener(leakCanaryProxy));
  }
  ...
}

public final class LoginController extends BindableBaseController<LoginControllerBinding> {
  @Override protected void injectDependencies() {
    ComponentFinder.<LoginActivityComponent>findActivityComponent(getActivity()).plus(
        new LoginControllerModule()).inject(this);
  }
  ...
}

the error: “Note: Generating a MembersInjector for ***.login.LoginController. Prefer to run the dagger processor over that class instead. Error:(23, 46) error: cannot find symbol class LoginControllerBinding where B is a type-variable: B extends ViewDataBinding declared in class BindableBaseController_MembersInjector”

the generated members injector:

@Generated(
  value = "dagger.internal.codegen.ComponentProcessor",
  comments = "https://google.github.io/dagger"
)
public final class BindableBaseController_MembersInjector<B extends ViewDataBinding>
    implements MembersInjector<BindableBaseController<LoginControllerBinding>> {
  private final Provider<LeakCanaryProxy> leakCanaryProxyProvider;

  public BindableBaseController_MembersInjector(Provider<LeakCanaryProxy> leakCanaryProxyProvider) {
    assert leakCanaryProxyProvider != null;
    this.leakCanaryProxyProvider = leakCanaryProxyProvider;
  }

  public static <B extends ViewDataBinding>
      MembersInjector<BindableBaseController<LoginControllerBinding>> create(
          Provider<LeakCanaryProxy> leakCanaryProxyProvider) {
    return new BindableBaseController_MembersInjector<B>(leakCanaryProxyProvider);
  }

  @Override
  public void injectMembers(BindableBaseController<LoginControllerBinding> instance) {
    if (instance == null) {
      throw new NullPointerException("Cannot inject members into a null reference");
    }
    ((BaseController) instance).setupLeakCanary(leakCanaryProxyProvider.get());
  }
}

Is there any way to make sure the generated data binding class is generated and available to use by dagger’s generated code?

[krakowski]

Sure, opened #698 just now. Thanks.