Question

//What is the output?

import java.util.HashMap;

public class AirportCodes {

   public static void main (String[] args) {

      HashMap<String, String> airportCode = new HashMap<String, String>();

      airportCode.put("GRX", "Granada, Spain");

      airportCode.put("ALB", "Albany, USA");

      airportCode.put("IWJ", "Iwami, Japan");

      System.out.print("ALB: ");

      System.out.println(airportCode.get("ALB"));

      airportCode.put("IWJ", "Ivalo, Finland");

      System.out.print("IWJ: ");

      System.out.println(airportCode.get("IWJ"));

   }

}

Answer 1

ALB: Albany, USA
IWJ: Ivalo, Finland

Explanation:
-------------
HashMap<String, String> airportCode = new HashMap<String, String>();
airportCode.put("GRX", "Granada, Spain");
airportCode.put("ALB", "Albany, USA");
airportCode.put("IWJ", "Iwami, Japan");
// -> At this point airportCode dictionary is {ALB=Albany, USA, GRX=Granada, Spain, IWJ=Iwami, Japan}
System.out.print("ALB: ");
System.out.println(airportCode.get("ALB")); // so, this prints ALB: Albany, USA

airportCode.put("IWJ", "Ivalo, Finland");   // This changes airportCode to {ALB=Albany, USA, GRX=Granada, Spain, IWJ=Ivalo, Finland}

System.out.print("IWJ: ");
System.out.println(airportCode.get("IWJ")); // so, this prints IWJ: Ivalo, Finland