OrderRepositoryInMemory

OrderRepositoryInMemory.java

static class OrderRepositoryInMemory implements OrderRepository {
    private final Map<Long, Order> orders = new ConcurrentHashMap<>();
    private final AtomicLong idGenerator = new AtomicLong(1);

    public Order save(Order order) {
        if (order.getId() == null) {
            Long id = idGenerator.getAndIncrement();
            Order savedOrder = new Order(id, order.getItems());
            orders.put(id, savedOrder);
            return savedOrder;
        } else {
            orders.put(order.getId(), order);
            return order;
        }
    }

    public Optional<Order> findById(Long id) {
        return Optional.ofNullable(orders.get(id));
    }

    public void clear() {
        orders.clear();
        idGenerator.set(1);
    }
}