set集合转成逗号间隔的字符串

分两步

1. 将set转为数组set.toArray();

2.将数组转为逗号间隔的字符串 StringUtils.join(arr,",")

代码如下:

        Set<String> set = new HashSet<>();
        set.add("hello1");
        set.add("hello2");
        set.add("hello3");
        Object[] arr = set.toArray();
        System.out.println(StringUtils.join(arr, ","));

输出结果:

hello1,hello2,hello3