public class OopBankAccount { private Integer number; private Integer balance; public OopBankAccount(Integer number, Integer balance) { this.number = number; this.balance = balance; } void deposit(Integer amount) { this.balance += amount; } void withdraw(Integer amount) { this.balance += amount; } void transfer(OopBankAccount destination, Integer amount) { this.withdraw(amount); destination.deposit(amount); } }