AccountTest.java

public class AccountTest {
  public static void main(String[] args) {
    Account account = new Account("111-22-33-4444");
    System.out.println("Остаток на счету " + account.number + ": " + account.getBalance());

    account.pay(3);
    System.out.println("Остаток на счету " + account.number + ": " + account.getBalance());
  }
}



public class Account {
  public final String number;
  private int balance = 0;

  public Account(String number) {
    this.number = number;
  }

  public int getBalance() {
    return balance;
  }

  public void pay(int amount) {
    balance = balance - amount;
  }
}