如何覆盖等于和哈希码到列表 <Long> 参数

Question

I have one class attribute called groups:

private List<Long> groups;

Can i use this attribute inside my equals like this:

if(!groups.equals(other.groups))
  return false

Answer 1

The answer to your updated question is: it depends on particular criterias for equality.

Default equals method for list compares size and all corresponding elements. It means that if lists have the same elements but in different orders they are not equal. If it fits your equality conditions then you can surely use it. If not, you have to compare lists manually according to your needs.

Answer 2

You cannot. The List interface specifies its equals and hashCode contract and any implementation that changed that would be in violation.