您需要识别相应的人员实例 - 我不知道您如何存储它们，您没有表明：每次添加日期时都会重新创建Person实例，因此它不能存在。



但是一旦你拥有了Person，就很容易：

You need to identify the appropriate person instance - and I have no idea how you are storing them, you don't show that: the Person instance is created anew each time you add a a date, so it can't be there.

But once you have the Person, it's easy:

myPerson.numberOfDates.add(dates);

BTW：尽量避免将事物命名为复数，除非它们是一个集合：Dates是一个单日期存储对象，因此它应该是Date，而People应该是人 - 但你似乎也有一个班级......这让人感到困惑！

BTW: try to avoid naming things as plurals unless they are a collection: "Dates" is a single date storage object, so it should be "Date", and "People" should probably be "Person" - but you appear to have a class for that as well...which gets confusing!