Java

Test.java

class Test {
  public static void main(String[] args) {
    System.out.println("Test");
  }
}

bash

>javac Test.java
>java Test
Test

Index.java

package test;

public class Index {
  public static void main(String[] args) { 
    TokyoService tokyo = new TokyoService();

    for (String city : tokyo.getCities()) {
      System.out.println(city);
    }

    OsakaService osaka = new OsakaService();
    System.out.println(osaka.getCity(0));
  }
}

IPrefecture

package test;

public interface IPrefecture {
  String[] getCities();
  // オーバーロード
  String getCity(int id);
}

TokyoService

package test;

public class TokyoService implements IPrefecture {
  static final String[] cities = {"中央区", "浪速区"};
    public TokyoService() {
    System.out.println("Osaka");
    }

    @Override
    public String[] getCities() {
        return cities;
    }

    @Override
    public String getCity(int id) {
        return cities[id];
    }
}

OsakaService

package test;

public class OsakaService implements IPrefecture {
  static final String[] cities = {"渋谷区", "新宿区"};
  public OsakaService() {
    System.out.println("Osaka");
  }

  @Override
  public String[] getCities() {
    return cities;
  }

  @Override
  public String getCity(int id) {
    return cities[id];
  }
}