3) Реализации (OCP + LSP)

3) Реализации (OCP + LSP)

// OCP+LSP: можно подставить любую оплату/уведомление без изменения сервисов
public final class CardPayment implements Payment {
    @Override public PaymentResult pay(Money amount) {
        // ... вызов платёжного шлюза ...
        return new PaymentResult(true, "tx-card-123", "Paid by card");
    }
}

public final class PaypalPayment implements Payment {
    @Override public PaymentResult pay(Money amount) {
        return new PaymentResult(true, "tx-pp-987", "Paid by PayPal");
    }
}

public final class EmailNotifier implements Notifier {
    @Override public void send(String to, String message) {
        System.out.printf("EMAIL → %s :: %s%n", to, message);
    }
}

public final class SmsNotifier implements Notifier {
    @Override public void send(String to, String message) {
        System.out.printf("SMS → %s :: %s%n", to, message);
    }
}

public final class NoDiscount implements DiscountPolicy {
    @Override public Money apply(Money amount) { return amount; }
}

public final class TenPercentDiscount implements DiscountPolicy {
    @Override public Money apply(Money amount) {
        var d = amount.amount().multiply(java.math.BigDecimal.valueOf(0.9));
        return new Money(amount.currency(), d);
    }
}

public final class InMemoryOrderRepository implements OrderRepository {
    private final java.util.Map<String, Order> storage = new java.util.concurrent.ConcurrentHashMap<>();
    @Override public void save(Order order) { storage.put(order.id(), order); }
}