Hi,

I found an error in the book Hibernate in Action, on page 334.

On that page is a class UserId with an equals method which says on line 3:


This line will not compile!! It should of course be:


thanx,
Jan Hoeve

Thanks, added to Errata

Just a tip...

This is a fairly common bug, especially for people new to coding in Java or C++ (identical syntax). There are a couple of ways to catch it before it bites you.

1. Eclipse has an optional warning called "Possible accidental boolean assignment (e.g. if (a=b))". Turn this on! Other IDEs may have a similar feature -- if not, they should!

2. Swap the values so that the constant (in this case, "null") is on the left side. Since the constant cannot be assigned a value using "=", this will cause a compile error. This is a good practice to get used to.