Lab Exam 21/11/2006

We want to realize a program for managing credit card accounts. For each account, the following information is stored:

Part 1. Write a class CCAccount that implements the following methods:

CCAccount(String owner, String ccn, double me) : constructor that creates an object representing a credit card account whose owner is owner, whose credit card number is ccn, whose maximum allowed expenses is me, and whose initial expenses are 0.
String getOwner() : that returns the name of the owner of the account;
String getNumber() : that returns the credit card number for the account;
double getMaxExpenses() : that returns the maximum allowed expenses for the credit card account;
double getExpenses() : that returns the current expenses for the credit card account;
double spend(double a) : if the amount of Euro a does not exceed the remaining allowed expenses (which are calculated as the difference between the maximum allowed expenses and the current expenses), then a is added to the current expenses, and the new remaining allowed expenses are returned. Otherwise the credit card account is not changed, and -1 is returned;
double payBack() : that sets the current expenses to 0, and returns the current expenses (before they were set to 0);
String toString() : that returns a string with all the information about the credit card account.

Part 2. Write a class UseCCAccount, client of CCAccount, that contains the following public static method:

static double getMinRemainingExpenses(CCAccount a1, CCAccount a2) : that, given two credit card accounts a1 and a2, returns the minimum among the remaining expenses of a1 and a2 that is different from 0. More precisely,
- if for both accounts the remaining expenses are positive, the minimum of the two remaining expenses is returned;
- if for only one of the two accounts the remaining expenses are positive, that amount is returned;
- if for both accounts the remaining expenses are 0, then 0 is returned.