import java.util.HashMap;

import java.util.Map;

public class SimpleMap

{

public static void main(String[] args)

{

SimpleMap simpleMap = new SimpleMap();

simpleMap.demo();

}

private void demo()

{

Map<String, String> countries = new HashMap<String, String>();

countries.put("USA", "United States");

countries.put("MEX", "Mexico");

countries.put("CAN", "Canada");

System.out.println(countries.get("USA"));

System.out.println(countries.get("CAN"));

countries.put("USA", "United States 2");

System.out.println(countries.get("USA"));

countries.remove("USA");

System.out.println(countries);

}

}