java8 将一个 List 转化为 指定字符分隔的字符串

使用String.join() 工具类

List<String> strings = new ArrayList<>(); strings.add("id"); strings.add("name"); strings.add("sex");

String join = String.join(",", strings);
//输出结果是：id，name，sex

使用Java8 Stream 流

`List cities = Arrays.asList(
"Milan",
"London",
"New York",
"San Francisco");

     String citiesCommaSeparated = cities.stream()
             .collect(Collectors.joining(","));
     System.out.println(citiesCommaSeparated);`