question 8.4

Hi guys

please help, i'm unsure of what is needed in question 8.4 - what exactly does "build indices" translate to?

also, i have a problem with the address class - i have it defined as:

-----------------------
public class Customer {
//public constructors
public Customer() {};
.
.
.
//nonpublic auxiliary methods or nested classes
public class Address {
public Address(){};
String street;
String city;
String state;
String country;
int postalcode;
}
}
----------------------

and then get an error "an enclosing instance that contains Customer.Address is required" when trying to instantiate address as:

Customer.Address add = new Customer.Address();