java - 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

Use reduce

Stream.of("1","2","3","4").reduce((a,b) -> a +"," +b))

Answer 2

If you are like me and don’t understand what reduce does

String.join(",", stringStream.collect(Collectors.toList()));

It’s a bit difficult to change your thinking

Answer 3

Stream.of(1, 2, 3, 4).reduce(new StringBuilder(), (sb, s) -> sb.append(s).append(','), StringBuilder::append).toString();