[SOLVED] Java Streams - check if list is null

Java Streams - check if list is null

I wonder what's teh best approach to check if list is null. In my Stream I call orElseThrow twice. It works but I don;t know if its correct? It looks a little bit ugly:

Optional.ofNullable(listCanBeNull)
                .orElseThrow(() -> new ResourceNotFoundException("the same error message"))
                .stream()
                .filter(configuration -> configuration.getId().equals(warehouseConfigurationId))
                .findAny()
                .orElseThrow(() -> new ResourceNotFoundException("the same error message"));

I have to throw error when list is null and when no item was found

Solution

An Optional::ofNullable can be turned into a (possibly empty) Stream, or you can immediately use Stream::ofNullable. And do a flatMap.

Stream.ofNullable(listCanBeNull)
    .flatMap(List::stream)
    .filter(configuration -> configuration.getId().equals(warehouseConfigurationId))
    .findAny()
    .orElseThrow(() -> new ResourceNotFoundException("the same error message"));