在 Java 8 Comparator 的 Sort 方法中切换 Sort 过滤器参数

Question

How to change the sort parameter based on a null check in Java 8 stream.

Example:

myList = myList .stream().sorted(Comparator.comparing(Profile::getFirstName)).collect(Collectors.toList());

Here if getFirstName turns out NULL, I want to use another value getLastName.

Like:

if(Profile.getFirstName()==null)

Sort using Profile.getLastName()

else

Sort using Profile.getFirstName()

Answer 1

...sorted(Comparator.comparing(x -> x.getFirstName() == null ? x.getLastName() : x.getFirstName()))....

Answer 2

我这样做了：

 myList = myList.stream().sorted(Comparator.comparing(profile->profile.getFirstName()==null? profile.getLastName():profile.getFirstName())).collect(Collectors.toList()); 

Answer 3

    myList.stream().sorted((a, b) -> {
        if(a.getFirstName() != null && b.getFirstName() != null) {
            return a.getFirstName().compareTo(b.getFirstName());
        }

        if (a.getLastName() != null && b.getLastName() != null) {
            return a.getLastName().compareTo(b.getLastName());
        }

        return 0;
    });