dagger 예제

Bk.java

public class Bk {
    @Inject
    public Bk() {

    }

    public String helloworld() {
        return "Hello world";
    }
}

MainActivity.java

public class MainActivity extends DaggerAppCompatActivity {
    @Inject
    Bk mBk; // 알아서 instance 됨 

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        MainViewModel vm = ViewModelProviders.of(this).get(MainViewModel.class);
        vm.netInfo.set(mBk.helloworld());

        ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        binding.setModel(vm);
    }
}

MainApp.java

public class MainApp extends DaggerApplication {
    @Override
    protected AndroidInjector<? extends DaggerApplication> applicationInjector() {
        return DaggerMyAppComponent.builder().application(this).build();
    }
}

MyAppComponent.java

@Component( modules = { AndroidInjectionModule.class, MyAppModule.class })
public interface MyAppComponent extends AndroidInjector<MainApp> {
    @Component.Builder
    interface Builder {
        @BindsInstance
        MyAppComponent.Builder application(Application application);
        MyAppComponent build();
    }
}

MyAppModule.java

@Module
public abstract class MyAppModule {
    @ContributesAndroidInjector
    abstract MainActivity contributeActivityInjector();
}