Account.java

public class Account {
    private String accountNumber;
    private double balance;

    public Account() {
        this("empty", 0.0);
    }

    public Account(String accountNumber, double balance) {
        this.accountNumber = accountNumber;
        this.balance = balance;
    }

    public String getAccountNumber() {
        return accountNumber;
    }

    public double getBalance() {
        return balance;
    }

    public void deposit(double money) {
        balance += money;
    }

    public double withdraw(double money) {
        balance -= money;
        return money;
    }
}