amitkma

class ServiceLocator...
    private static ServiceLocator sInstance;
    public static void load(ServiceLocator arg) {
        sInstance = arg;
    }
    private Map services = new HashMap();
    public static Object getService(String key){
        return sInstance.services.get(key);
    }
    public void loadService (String key, Object service) {

amitkma

@Module
public class BookFinderModule {
    @Provides
    BookFinder provideBookFinder() {
        return new OxfordBookFinder();
    }
    @Provides
    @LocalFinder  
    BookFinder provideLocalBookFinder() {
        return new LocalLibraryBookFinder();

amitkma

public interface BookFinder {
    List findAll();
}

class Library…
  private BookFinder finder;
  public Library() {
    finder = new(RemoteBookFinder("https://oxfordlibrary.com/books"); // Can be a local database implementation as well.
  }
  ....

amitkma

class Library…
  public Book[] booksAuthoredBy(String arg) {
      List allBooks = finder.findAll();
      for (Iterator it = allBooks.iterator(); it.hasNext();) {
          Book book = (Book) it.next();
          if (!book.getAuthor().equals(arg)) it.remove();
      }
      return (Book[]) allBooks.toArray(new Book[allBooks.size()]);
  }

amitkma

@Inject Map<MessageType, Provider<ViewHolder>> mViewHolders

//...
for (Message message : messages) {
  mViewHolders.get(message.getType()).get().display(message);
}

amitkma

@Module
public abstract class ViewHolderModule {

    @Binds
    @IntoMap
    @ViewHolderKey(MessageType.TEXT_MESSAGE_TYPE)
    abstract ViewHolder bindUserViewModule(TextMessageViewHolder textMessageViewHolder);
  
    @Binds
    @IntoMap

amitkma

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@MapKey
@interface ViewHolderKey {
    MessageType value();
}

amitkma

public enum MessageType {
  TEXT_MESSAGE_TYPE,
  IMAGE_MESSAGE_TYPE,
  INFO_MESSAGE_TYPE;
}

amitkma

public class MainPresenterImpl implements MainContract.Presenter {

    private final MainContract.View mView;
    private final DataManager mDataManager;

    // Constructor with view and datamanger parameters.
    public MainPresenterImpl(MainContract.View view, DataManager dataManager) {
        this.mView = view;
        mDataManager = dataManager;
        mView.setPresenter(this); // Set presenter to the mView.

amitkma

public class MainActivity extends AppCompatActivity implements MainContract.View, View.OnClickListener {

    // Contract Presenter
    private MainContract.Presenter mPresenter;
    ......
    // Other fields

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