我上来就直接return
不讲武德

class Solution {
    public String reverseWords(String s) {
        return new StringBuilder(Stream.of(s.split(" ")).map(x -> new StringBuilder(x).reverse()).collect(Collectors.joining(" "))).reverse().toString();
    }
}

如果看得懂就看下面的清楚些

class Solution {
    public String reverseWords(String s) {
     return new StringBuilder(
                Stream.of(s.split(" "))
                        .map(x -> new StringBuilder(x).reverse())
                        .collect(Collectors.joining(" "))
        ).reverse().toString();
}