Attach Link
https://baijiahao.baidu.com/s?id=1618298449551241841&wfr=spider&for=pc
Simple, polymorphic piece may also need to look at their own Baidu, Map map = new HashMap (); I think this should be considered a multi-state (see to guide us there is not a thank you!)
Polymorphic three conditions: inherited, rewrite, parent class object reference to subclass object (upcast)