java-design-patterns/dirty-flag/src/main/java/com/iluwatar/dirtyflag/World.java

/*
 * The MIT License
 * Copyright © 2014-2019 Ilkka Seppälä
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package com.iluwatar.dirtyflag;

import java.util.ArrayList;
import java.util.List;

/**
 * A middle-layer app that calls/passes along data from the back-end.
 *
 * @author swaisuan
 */
public class World {

  private List<String> countries;
  private final DataFetcher df;

  public World() {
    this.countries = new ArrayList<String>();
    this.df = new DataFetcher();
  }

  /**
   * Calls {@link DataFetcher} to fetch data from back-end.
   *
   * @return List of strings
   */
  public List<String> fetch() {
    var data = df.fetch();
    countries = data.isEmpty() ? countries : data;
    return countries;
  }
}