如何在java中添加两个可选

Question

Optional<Long>totalLanding= ....(get it from somewhere);
Optional<Long>totalSharing = ...(get it from somewhere);

Optional<Long>total = totalLanding+totalSharing;

Answer 1

使用streams怎么样？

Optional<Long> total = Stream.of(totalLanding,totalSharing)
                             .filter(Optional::isPresent)
                             .map(Optional::get)
                             .reduce(Long::sum);

顺便说一句，我会使用optionallong而不是optionallong。

解决办法类似：

OptionalLong total = Stream.of(totalLanding,totalSharing)
                           .filter(OptionalLong::isPresent)
                           .mapToLong(OptionalLong::getAsLong)
                           .reduce(Long::sum);