CityOperations

```
public interface CityOperations
```

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`int`	`connectCities(int cityId1, int cityId2, int distance)`	Connects two cities.
`int`	`createCity(java.lang.String name)`	Creates new city.
`java.util.List<java.lang.Integer>`	`getCities()`	Gets all cities
`java.util.List<java.lang.Integer>`	`getConnectedCities(int cityId)`	Get connected cities.
`java.util.List<java.lang.Integer>`	`getShops(int cityId)`	Get shops in the city.

- Method Detail
  - createCity
```
int createCity(java.lang.String name)
```
    Creates new city.
    
    Parameters:
    
    name - the name of the city. Name of the cities must be unique.
    
    Returns:
    
    city id, or -1 on failure
  - getCities
```
java.util.List<java.lang.Integer> getCities()
```
    Gets all cities
    
    Returns:
    
    ids of cities, null if failure
  - connectCities
```
int connectCities(int cityId1,
                  int cityId2,
                  int distance)
```
    Connects two cities. There can be max one line between cities.
    
    Parameters:
    
    cityId1 - id of the first city
    
    cityId2 - id of the second city
    
    distance - distance between cities (distance is measured in days)
    
    Returns:
    
    line id, or -1 on failure
  - getConnectedCities
```
java.util.List<java.lang.Integer> getConnectedCities(int cityId)
```
    Get connected cities.
    
    Parameters:
    
    cityId - id of the city that connections are asked for
    
    Returns:
    
    list of connected cities ids
  - getShops
```
java.util.List<java.lang.Integer> getShops(int cityId)
```
    Get shops in the city.
    
    Parameters:
    
    cityId - id of the city
    
    Returns:
    
    list of ids of shops, null if failure