Java™ How to Program, Seventh Edition

M.8. Class BankDatabase

Class BankDatabase (Fig. M.7) models the bank’s database with which the ATM interacts to access and modify a user’s account information. We determine one reference-type attribute for class BankDatabase based on its composition relationship with class Account. Recall from Fig. 10.21 that a BankDatabase is composed of zero or more objects of class Account. Line 6 implements attribute accounts—an array of Account objects—to implement this composition relationship. Class BankDatabase has a no-argument constructor (lines 9–14) that initializes accounts to contain a set of new Account objects. For the sake of testing the system, we declare accounts to hold just two array elements (line 11), which we instantiate as new Account ...