Dependency Injection

We use dependency injection in this project so we can easily test our service layer.

To use services inside Activities/Fragments you need to do the following.

Lets say we created a new activity/fragment ViewFriends

1. Add your inject(ClassName className) entry into the di/ServiceComponent.java file:

    void inject(ViewFriends viewFriends);

2. In your onCreate() method in the activity, ensure you inject from the DI source before you call any injected variables:

    protected void onCreate(Bundle savedStateBundle) {
        super.onCreate(savedStateBundle);
        ContextGrabber.get().di().inject(ViewFriends.this);
    }

3. Now above in your properties, you can easily inject dependencies. This is a full example.

class ViewFriends extends AppCompatActivity {

    @Inject
    AuthenticationService auth;


    protected void onCreate(Bundle savedStateBundle) {
        super.onCreate(savedStateBundle);
        ContextGrabber.get().di().inject(ViewFriends.this);
        // this will get the auth instance (which is a singleton) and output the username
        Log.i("DI/TEST", auth.getUsername());
    }

}

This eliminates the need to use new AuthenticationService() and allows you to use complex services (see: MoodEventService) without injecting a ton of dependencies manually.