轉載來源：https://www.cnblogs.com/hmgx/p/11942342.html
1、將list轉化爲逗號分割的字符串
String str = String.join(",", list);
String str = StringUtils.json(list.toArray(), ",");
2、將逗號分隔的字符串轉換爲List
List<String> list = Arrays.asList(str.split(","));
List<String> list = Arrays.asList(StringUtils.split(str, ","));
3、將字符串中的字符替換
String newStr = str.replace("需替換的字符", "目標字符");