Stream 元素是字符串，用逗号拼接

Question

Stream.of("1","2","3","4")这个是输入
我想得到1,2,3,4的输出，怎么写？

Answer 1

Stream.of("1", "2", "3", "4").collect(Collectors.joining(","))

Answer 2

如果你和我一样不懂reduce事干啥的话String.join(",", stringStream.collect(Collectors.toList()));转变思维有点难啊