Example of Contract interface in MVP pattern

ShoppingContract.java

package me.fleka.deltacity.presentation.shopping;

import java.util.List;
import me.fleka.deltacity.domain.models.Category;
import me.fleka.deltacity.domain.models.Shop;
import me.fleka.deltacity.presentation.BasePresenter;
import me.fleka.deltacity.presentation.BaseView;

/**
 * Created by mladenrakonjac on 14/09/16.
 */
public interface ShoppingContract {

  interface View extends BaseView<Presenter> {

    void setLoadingIndicator(boolean active);

    void showCategories(List<Category> categoryList);

    void showNoInternetConnection();

    void showLoadingCategoriesError();

    void showListOfFoundedShopForSearch(List<Shop> shopList);

    void showNoShopsFound();
  }

  interface Presenter extends BasePresenter {

    void loadCategories();

    void openCategory(int categoryId);

    void searchShop(String searchText);

    void openShop(int shopId);

    void cleanSearch();
  }
}