Populating a map that has been instanced

Question

Im trying to populate a map that has been declared as an instance variable but nothing happens when i execute the code.

Here is my class (very basic/early)

public class RacingDrivers
{
private Map<String, String> racingNumbers;

/**
* Constructor for objects of class RacingDrivers
*/
public RacingDrivers()
{
   racingNumbers = new HashMap<String, String>();
}

/**
* A method to populate the racingNumbers map.
* 
* 
*/
public void populateMap()
{
  racingNumbers.put("44", "Lewis Hamilton");
  etc etc

}

Then i execute this code:

RacingClub RC = new RacingClub();
RC.populateMap();

RC is created but the map is not populated?

Answer 1

You're creating an instance of class RacingClub.

The racingNumbers Map is an instance field of class RacingDrivers.

The Map is initialized in the constructor of the RacingDrivers class.

Answer 2

you initialize the class RacingDrivers

and then call

RacingDrivers  rc = new RacingDrivers();

rc.populateMap();