[FIXED] How to make return type nullable using Optional<T> etc?

Issue

I have the following method that returns DemoDTO and if it is not found, return exception.

public DemoDTO findShallowByUuid(UUID uuid) {
    return demoRepository.findShallowByUuid(uuid)
            .orElseThrow(() -> new EntityNotFoundException("Not found"));
}

However, I want to let the method to return a nullable DemoDTO instead of throwing error. For this purpose, I converted its type and the related return types to Optional<DemoDTO> or Optional<T>, but it caused some problems regarding to the related DTO. After I updated the constructor parameters to Optional<T>, the other part of the app that using this DTO complained.

I am not sure converting to Optional<T> is a good idea or not. If it is a good idea, should I add another constructor to the DemoDTO? I am not sure if it is a good solution as it will also require some changes for the property types. Any idea?

Solution

To put my comment into an answer, this would be the most elegant way based on your requirements:

public DemoDTO findShallowByUuid(UUID uuid) {
    return demoRepository.findShallowByUuid(uuid).orElse(null);
}

But be sure that the calling code correctly handles null to avoid NullPointerExceptions.

Answered By - jmizv