.filter(x->x!=null) == .filter(Objects::nonNull)

有趣的是你已经使用了方法参考（但没看到这一个）：

It's interesting that you already use a method reference in(but failed to see this one):

max(Date::compareTo)

此外，您显然会返回日期但是来自可选<日期> ，您应该收到警告（如果使用IDEA），直接在可选$ c $上调用获取是不安全的c>。

Also you are obviously returning a Date but from an Optional<Date>, you should get a warning (if using IDEA) that it's not safe to call get directly on an Optional.

你还可以用 max（Date :: compareTo） > max（Comparator.naturalOrder（））因为日期已经可比较。

And you could also replace that max(Date::compareTo) with max(Comparator.naturalOrder()) since Date is already Comparable.