Implementation of Contract.Presenter in MVP pattern

ShoppingPresenterImpl.java

package me.fleka.deltacity.presentation.shopping;

import android.support.annotation.NonNull;
import java.util.List;
import me.fleka.deltacity.data.category.CategoryDataSource;
import me.fleka.deltacity.domain.models.Category;

import static com.google.gson.internal.$Gson$Preconditions.checkNotNull;

/**
 * Created by mladenrakonjac on 14/09/16.
 *
 * Listens to user actions from the UI ({@link ShoppingFragment}) , retrieves the data and
 * updates the UI as required.
 */
public class ShoppingPresenterImpl implements ShoppingContract.Presenter,
    CategoryDataSource.LoadCategoriesCallback {

  private final CategoryDataSource mCategoryRepository;

  private final ShoppingContract.View mShoppingView;

  /**
   * Creates a presenter for Categories presentation and Shop searching
   * @param categoryRepository a repository fo data for categories
   * @param shoppingView search shop/ categories view
   */
  public ShoppingPresenterImpl(@NonNull CategoryDataSource categoryRepository,
      @NonNull ShoppingContract.View shoppingView) {

    mCategoryRepository = checkNotNull(categoryRepository);
    mShoppingView = checkNotNull(shoppingView);
    mShoppingView.setPresenter(this);
  }

  @Override public void loadCategories() {
    mShoppingView.setLoadingIndicator(true);
    mCategoryRepository.getCategories(this);
  }

  @Override public void openCategory(int categoryId) {
    //Todo
  }

  @Override public void searchShop(String searchText) {
    //Todo
  }

  @Override public void openShop(int shopId) {
    //Todo
  }

  @Override public void cleanSearch() {
    //Todo
  }

  @Override public void start() {
    mShoppingView.setLoadingIndicator(true);
    loadCategories();
  }

  @Override public void onCategoriesLoaded(List<Category> categories) {
    mShoppingView.setLoadingIndicator(false);
    mShoppingView.showCategories(categories);
  }

  @Override public void onDataNotAvailable() {
    mShoppingView.showNoShopsFound();
  }
}