List集合转换String，两种比较好用的处理方式

1.采用java8 String.join 字符串拼接

public static void main(String[] args) {
        List<String> list = Lists.newArrayList();
        list.add("测试1");
        list.add("测试2");
        list.add("测试3");
        String join = String.join(",", list);
        System.out.println("join{}"+join);
    }

输出：join{}测试1,测试2,测试3

2.采用guava的Joiner字符串拼接

 public static void main(String[] args) {
        List<String> list = Lists.newArrayList();
        list.add("测试1");
        list.add("测试2");
        list.add("测试3");
        String join = Joiner.on(",").join(list);
        System.out.println("join{}"+join);
    }

输出：join{}测试1,测试2,测试3