如何将依赖项注入和匕首用于onCreate（）方法中已创建的视图

Question

I am new to dependency injection. I wanted to avoid using static methods. For simplicity i am showing the code that is only relevant.

Here is my code:

public class MainActivity extends AppCompatActivity {
     private ImageView mFavorites_fab;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         mFavorites_fab = (ImageView) findViewById(R.id.favorites_fab);
     }

     void vibrateFab(Context context) {   //Function to be called using DI
         Log.v(TAG, "vibrate fab" +context);

         Animation vibrateAnimation = AnimationUtils.loadAnimation(context, R.anim.vibrate);
         mFavorites_fab.setAnimation(vibrateAnimation);
     }

I wanted to call vibrateFab function from another class using Dependency injection

This is how I am trying to call.

Module:

@Module
public class MainActivity_Module {

    @Provides
    @ActivityScope
    MainActivity providesMainActivity() {
        return new MainActivity();
    }
}

Component:

@Component(modules = MainActivity_Module.class)
@ActivityScope
public interface MainActivity_Component {
    void inject(Nearby_Viewpager_Stops nearby_viewpager_stops);
} 

Another class:

public class Nearby_Viewpager_Stops extends Fragment {
    @Inject
    MainActivity mainActivity;
    Context mContext;


    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        mContext = context;

        MainActivity_Component component = DaggerMainActivity_Component.builder().mainActivity_Module(new MainActivity_Module()).build();
        component.inject(Nearby_Viewpager_Stops.this);
        mMainActivity.vibrateFab(mContext);

    }

Now the problem is: In this line mFavorites_fab is null as I am using new instance of Main Activity.

 mFavorites_fab.setAnimation(vibrateAnimation);

How to overcome this?

Answer 1

Interesting. I don't think Dagger can give you dependices on .class it would need an object. The way to get this is * in your Application create an Application Component. ApplicationComponent would have a module provider. providing vibrateFab;

From your activity get access to the AcitivityComponet and then say inject into the class Now you can use ActivityInjector method to avoid some bipolate code

I would strongly recomemend following example http://www.vogella.com/tutorials/Dagger/article.html#exercise_androiddagger

Happy coding!!