📜  已设置 - 无论代码示例

📅  最后修改于: 2022-03-11 14:59:20.339000             🧑  作者: Mango

代码示例2
SET: Can only store unique values, 
     And does not maintain order
- HashSet can have null, order is not guaranteed
- LinkedHashSet can have null and keeps the order 
- TreeSet sorts the order and don't accept null