The discussion of equals() and hashCode() in the next-to-last paragraph on page 125 is either unclear. It reads:



However, the code sample provided above on the same page clearly does not use a getter method in the implementation of hashCode().

Is the code sample wrong? Or is the statement wrong? The paragraph continues by saying "This is important, since the object instance passed as other might be a proxy object, not the actual instance that holds the persistent state" which could lead one to believe that getter methods aren't really required for hashCode() (since there obviously is no other instance passed to hashCode()).

What's the right thing to do for hashCode()?

It is just important to reference the OTHER object via getter.

In the case of the example on page 125 the hashCode method has no such access (hashCode never has such an access since only the this reference is available). In case of the equals method the example accesses the other property with that.getUsername() which is the correct way.

Right, that much I understand. If that's all there is to it, then the statement should be changed to read:



My confusion about hashCode() comes from my lack of knowledge about Hibernate proxies. I wasn't sure whether Hibernate creates a subclass which doesn't override hashCode() but does override the getters. If that's the case, then I could understand the argument to use getters in hashCode() (and everywhere in equals(), not just for the other object).