Blog - Optional.orElse

Declaration.java

public T orElse(T other)
public T orElseGet(Supplier<? extends T> other)

DeclarationOne.java

public Optional<Inventory> findInventoryByUser(User user)

First.java

public Inventory getInventory(User user) {
    Optional inventory = findInventoryByUser(User user);
  
    if (inventory.isPresent()) {
        return inventory.get();
    } else {
        throw new NotFoundException();
    }
}

Four.java

public Inventory getInventory(User user) {
    return findInventoryByUser(userUuid)
        .orElseGet(() -> createInventory(user));
}

Second.java

public Inventory getInventory(User user) {
    return findInventoryByUser(User user)
        .orElseThrow(() -> new NotFoundException());
}

Third.java

public Inventory getInventory(User user) {
    return findInventoryByUser(userUuid)
        .orElse(createInventory(user));
}