参考：
https://www.cnblogs.com/CarpenterLee/p/6550212.html
写的很好，
使用collect做字符串join，真的是过目不忘 0.0
// 使用Collectors.joining()拼接字符串 Stream<String> stream = Stream.of("I", "love", "you"); //String joined = stream.collect(Collectors.joining());// "Iloveyou" //String joined = stream.collect(Collectors.joining(","));// "I,love,you" String joined = stream.collect(Collectors.joining(",", "{", "}"));// "{I,love,you}"
原文：https://www.cnblogs.com/timetellu/p/12886431.html