public / protected / private

class Account {
    private int balance;
 
    public void deposit(int amount) {
        if (amount <= 0) {
            throw new IllegalArgumentException("amount must be positive");
        }
        balance += amount;
    }
 
    public int getBalance() {
        return balance;
    }
}
 
void main() {
    Account account = new Account();
    account.deposit(100);
    IO.println(account.getBalance());
}

100

// src/Shop.java
public class Shop {
    void pay(Account account) {
        account.balance = 1_000_000; // error: balance has private access in Account
    }
}