You are almost there. You have:
public Location(String aCity, double aLatitude, double aLongitude)
{
String city = aCity;
double latitude = aLatitude;
double longitude = aLongitude;
}
You are declaring local variables in the constructor. You actually want to be declaring fields:
public class Location {
private String city;
private double latitude;
private double longitude;
public Location(String aCity, double aLatitude, double aLongitude)
{
city = aCity;
latitude = aLatitude;
longitude = aLongitude;
}
...
}
Check out the official tutorial on declaring member variables. It is concise and well-written and will give you a better idea of what is going on.